Zagazig University Faculty of Veterinary Medicine Dep. of Bacteriology, Mycology and Immunology
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Dr. Gamal A. Elmowalid
Immunolog y
Science concern with studying:
1- Protection against infection 2- Organization and homing of immune cells in immune organs 3- Mechanisms of secretion of immunological product as: Antibodies & Cytokines And their roles in ☻Protection ☻Diagnosis of infectious agents ☻Designing vaccines
Immunity Term immunity is derived from Latin word (immunis) = exempt from charges Immunity or resistance is a state of protection from infectious diseases through its inherited and acquired protection This immunity is conferred by immune system Immune system Is complicated collection of: Cells
Organs
Tissues
Fluids
That act in a very complicated manner to provide protection to the host
The main aims of immune system 1- protect body against infectious agent 2- Defense against non-infectious agents as: cancer Transplanted tissues 3- Confer immunity -- limit damage by infectious agents 4- induce memory response (successful immune response on re- infection) 5- Differentiate self from non-self
-1
Cells
A. Specific cell B- lymphocyte T- lymphocyte Interact with each M.O by special way Characters of specific cells: 1- Diversity تنتشر وتتوسع مع ملييين 2- Specificity في نفسM.Os ال الوقت 3- Memory response 4- Differentiate between self &non-self
B. Non-specific cell Granulocyte
Agranulocyte
Neutrophils Basophil Esinophil
Monocyte Macrophages Denderitic cells
Interact with any M.O by the same way
-2
Lymphoid organs and tissues هام جدا
Classified according to function to: Primary
secondary
MALT
Primary lymphoid organs.
Secondary lymphoid organs
[ Central ]
[ Peripheral }
the sites where lymphocytes
originate and mature 1- bone marrow, bone
marrow equivalent (bursa of Fabricius in birds)
The sites in which the
immune response develops 1- lymph nodes 2- spleen 3- tonsils
2- the thymus Its role
Its role
1- Hematopoiesis and
1- Trapping of antigen
lymphopoiesis
بيئة محيطة مناسبة
2- Provide appropriate
microenvironments for the development and maturation of lymphocytes.
3- Enable lymphocytes to
recognize foreign antigen. antigen
4- Enable lymphocytes to
distinguish self from non self.
and particulate
substances from the blood and lymphatic fluid.
2- Processing and
presentation of the تعاون trapped antigen to the lymphocytes.
3- Sites of immune cells interaction and cooperation
GALT = Gut-associated lymphoid tissue
MALT Mucosa associated lymphoid tissue
BALT = Bronchus-associated lymphoid tissue
SMLT = Sub -mucosal lymphoid
tissues of genitourinary tract
Ontogeny of the immune cells ( Hematopoiesis )
☯ Is a continuous process to maintains a steady state in which :
the production of mature blood cells
=
their loss
(principally from aging)
☯ Human being must produce :
3.7 x1011 WBCs / day.
☯ Hematopoiesis is regulated by complex mechanisms include: 1. Control of the levels and types of cytokines produced by stromal cells of B.M. B.M 2. The production of cytokines by other cell types, such as activated T cells and macrophage . 3. The regulation of the expression of receptors for cytokines in stem cells and progenitor cells. 4. The removal of some cells by controlled cell death .
Hematopoietic Hematopoietic stem stem cell cell
All All blood blood cells cells arise arise from from hematopoietic hematopoietic stem stem cell cell (HSC) (HSC) which which originates originates from from the the yolk yolk sac sac and and foetal foetal liver liver by by process process called called hematopoiesis hematopoiesis
HSC HSC characterizes characterizes by: by: 1. 1. 2. 2. 3. 3.
Their Their ability ability to to differentiate differentiate into into other other cell cell types types Their Their capacity capacity to to make make self-renewal. self-renewal. Their Their levels levels are are maintained maintained by by cell cell division division under under the the control control of of cytokines cytokines
☯ Hematopoiesis occurs in the bone marrow producing:
erythrocytes, platelets, monocytes, granulocytes, and B cells, precursors for T cells, natural killer (NK) cells, dendritic cells, and mast cells
☯ Two cytokines play a central role in hematopoiesis: IL 3 + colony-stimulating factors
myeloid cell development
&
IL 7 produced by stromal cells in the B.M
lymphoid cell development
Other cytokines are also involved in the process of hematopoiesis as IL-1, IL-2, IL-6
â˜Ż Then mature WBCs ( leukocytes) carried within the blood and lymph from primary lymphoid organs to secondary lymphoid organs then to sites of infection.
Thymu Thymuss
◘
The thymus is the site of T-cell development and maturation
◘ ◘
Situated above the heart
◘
Each lobule is organized into two compartments
It is a flat, bilobed organ ,each lobe is surrounded by a capsule and is divided into lobules, which are separated from each other by strands of connective tissue called trabeculae 1. the outer compartment (cortex) , is densely packed with thymocytes 2. the inner compartment (medulla) , is sparsely populated with thymocytes
◘
Thymus are crisscrossed by a stromal-cell network composed of : 1. Macrophages 2. Dendritic cells 3. Epithelial cells Some cortical epithelial cells have long interconnecting cytoplasmic extensions that form a network and interact with numerous thymocytes 4. Nurse cells One of thymic epithelial cells in the outer cortex have long membrane extensions that surround as many as 50 thymocytes, forming large multicellular complexes These cells make up the framework of the organ and contribute to the growth and maturation of thymocytes
Conclusion
Thymocyte
1. Thymic hormons
Mature T - Cells 2. Thymocyte growth factors 3. Cellular matrix specially nurse cells
Circulate
T cell Maturation With lymph or blood
1. Thymocyte leave B.M Thymus 2. Thymocyte enter the cortex of thymus . 3 Thymocy te
1. Thymic hormons 2. Thymocyte growth factors 3. Cellular matrix specially nurse cells
Migrate to
Mature T Cells Circulate
4. Interaction of T – Cells with other thymus cells -Induce the expression of T-cell receptorts , CD3 complex , CD4 , CD8 5. Clarified of these cells by stromal cells [ Macrophages , Denteritic cells ] which contain on it’s surface MHC class I , II ( important in recognition of T – cells( 6. T- lymphocytes selection A. Positive Positive selection selection A.
◘ takes place in the cortical region of the thymus ◘ interaction of thymocytes with cortical epithelial cells
The Thymocyte whose receptors able to bind to MHC of epithelial cell will receive a protective signal that prevents them from undergoing cell death
Thymocyte whose receptors are not able to bind MHC molecules would not interact with the thymic epithelial cells so, not receive the protective signal -- death by apoptosis
B. Negative Negative Selection Selection B.
Ensures Self-Tolerance
â—˜
thymocytes that survive positive selection comprises:
cells with lowaffinity receptors for MHC molecules
Survive & circulate
other cells with high -affinity receptors. undergo negative selection dendritic cells and macrophages bearing class I and class II MHC molecules interact with thymocytes bearing highaffinity receptors Negative selected cells will undergo death by apoptosis
7.
Apoptosi Cell death ( ( Programming s
1. Shrinkage of cells 2. Fragmentation of nucleus
Bleb
3. Cell membrane blebbing 4. Cell membrane , Cytoskeleton allow intact pieces of the cell to separate 5. recognized and phagocytosed by macrophages
Macrophages
CD4
+
-
+
-
CD8
+
-
-
+
Death
TH
TC
The relation relation between between thymus thymus and and The development of of immune immune response response development A. Neonatal thymectomy
B. Adult thymectomy
1.Drop in the levels of circulating lymphocytes
1.Circulating lymphocytes will decline progressively. progressively
2.Increase animal susceptibility to infection with subsequent immunodeficiency
2.Due to presence of lymphocytes reservoir in other body tissues, this effect will replenished over the time
3.Inability of animal to mount cell-mediated immune response
3.The ability to mount an immune response will gradually decrease. decrease
4.Animal can not reject tissue grafts
4.Delay in tissue graft rejection
5.The antibody response to T cell-dependent antigen is significantly inhibited. inhibited
5.Immune response against thymus-dependent antigens will be greatly affected 6.Continuous exposure to viral and parasitic infection (intracellular pathogens)
I-Classes I-Classes of of immunity immunity Non-specific immunity
هام جدا
Specific immunity
Innate or Inherited 1. Inherited
Adaptive or Acquired 1. Acquired
2. Front Line of host Defense
2. Consequent line of host defense
3. Immediate to early response (minutes – hours)
3. Immediate to late response
4. Not specific
4. specific
5. No memory response
5. Memory response
6. No anamnesis ( تذكرno magnitude 6. Anamnesis in response) 7. Do not rely on clonal expansion of Ag-specific lymphocytes
7. Rely on clonal expansion
8. Recognizes broad classes of pathogens
8. Recognize Ag with MHC
9. Can discriminate تميزbetween self and non-self
9. Only if MHC is present
10. Example :
10. Example :
✰ Fixed Defenses
Epithelium Phagocytes
يتكل علي
منسوخ
✰ T- lymphocyte
Cell-mediated response
✰ Complement System
Cascade of plasma proteins that opsonize pathogens and induce series of inflammatory responses ✰ Receptors
☞
✰ B- lymphocyte
Humoral response
Recognize broad range of 2 pathogens classes work together in orchestrated manner to 1. Eliminate pathogens 2. Protect against foreign invaders.
Differencebetween betweenBB&&TTlymphocyte lymphocyte Difference T - lymphocyte
B - lymphocyte
Specific cellular immunity
Specific humoral immunity
Complete its maturation in thymus
Its maturation and development in bone marrow (mammals) or bursa of fabricious (birds )
At periphery of lymph follicles
In centre of lymph follicles
Smaller ( 6-8 Îź )
Medium(9-10)or large (12-15)
Survive longer
Survive less than T-cell
Don’t divide at the site of inflammation
Divided to give small lymphocytes which developed into large lymphocytes
Function : Secrete inflammatory cytokines which differentiate TLC into : Effector cells Memory cell Both controlling: 1. Infected cells 2. Intracellular pathogen 3. Viral infection 4. Tumor control
Function : 1. Produce Ab to over come infection 2. Memory response
II - Classes of immunity
.A Cellular Specific
T - Cells
Non-specific
Phagocytic cells
.B Specific
Ab
Humoral ( Fluid) Non-specific
Complement IFN
T- helper
Lysozyme
T- cytotoxic T- suppressor T- delayed hypersensetivity A. A.NonNon- specific specific innate innate immunity immunity Basic inherited resistance to infectious diseases that individual or species possesses Represented by barriers: 1. Anatomical barriers 2. Biological barriers 3. Physiological barriers 4. Chemical mediators 5. Mechanical barriers (physical) 6. Inflammatory barriers 7. Phagocytic barriers
1.Anatomical 1.Anatomical barriers barriers
the first line of defense against pathogens and infection prevent the entry of pathogens and their spread in hosts Skin - 1 1 -Has a unique histological structure that enables it to be the first barrier of defense together with mucous membranes 2 - Prevents the penetration of most pathogens 3 - Inhibits most bacterial growth via its unique structure The epidermis thin layer
The dermis thicker layer
Contains several layers
Composed of C.T ,B.V, hair
epithelial cells
and sweat glands
of tightly packed
follicles, sebaceous glands,
No blood vessels Confer protection
Prevent pathogens invasion
1. Its continuous
1. Sebaceous glands-glands- sebum
through :
sloughing off and is
through:
(fatty acids + lactic acid )
constantly renewed
--⇩pH of the skin ( 3 – 5 )
prevent microbial
most microbes.
from below so it can colonization.
2. Its waterproofing
keratin that makes it
dry and impermeable to pathogens.
impossible for growth of
2. Skin glands also secrete lysozyme, lysozyme an enzyme can
break down the outer wall of certain bacteria.
3. Hair follicles---oily follicles-
Mucous membranes - 2
هام جدا
☺ cover respiratory, gastrointestinal, and urogenital tracts. ☺ Mucous membrane consists of: 1. underlying C.T 2. outer epithelial layer
3. mucous secretions 4. Cilia
mucous secretions 1. Mucous viscosity entraps M.Os 2. Dilution to irritants 3. The polysaccharides prevent M.Os from binding to their receptors in either epithelial or C.T cells 4. Contain IgA – block receptors on m.m – Neutralization of microbial toxin – Aggregate and agglutinate of m.o
Cilia covering mucous membranes of respiratory or alimentary tracts propel or sweep out mucous- entrapped pathogens from these tracts.
5. Defensene : – destruction of cell wall of gram +ve bacteria
Eye- 3 Tears contain lysozymes and phospholipase make cleavage to Gm-ve bacteria and destabilize bacterial membranes Ear - 4 Waxy materials ( low Ph and + chemical nature ) prevent M.Os entrance and growth Nose - 5 It’s mucous secreations make sticking to M.Oshair entrapped M.Os It’s
How How m.o m.o overcome overcome skin skin and and m.m m.m barriers barriers 1-Skin Skin 11. Through skin injury 2. Penetration of contaminated sharp object so, M.o reach to B.Vs then reach to suitable sites for growth and multiplication 3. Via insect bites Ex, • Malaria • Plague ( Yersenia Pestis via fleas bites) 3. Few bacteria can metabolize sebum and live as commensals in the skin Ex, • Teenager acne : caused by Staph. Epidermidis which invade hair follicle prevent L.A and F.A slight irritation to hair follicle inflammatory cells accumulate in this sites Mucousmembranes membranes 22- -Mucous 1) Influenza virus Has surface molecules neuraminidase that act as enzymes and dissolve this mucous and decrease viscosity so, free the virus from entrapping and can bind to its receptor and replicate.
2) Neisseria gonorrhea Which cause Proxilla disease السيلن, this bacteria have glycoproteins and glycolipids projections (fimbriae or pili) that enable them from binding firmly to the urogenital tract epithelia so they can’t swept out easily
3) Treponema palladium Corkscrew movement so can penetrate m.m cause sphilis الزهري
2.Biological 2.Biological barriers barriers
هام جدا
The normal flora of the skin and in the gastrointestinal tract can prevent the colonization of pathogenic bacteria by: )Biological value of micro flora( 1. Produce many antibacterial compounds , antimicrobial agents that inhibit invasion of pathogenic m.os 2. Compete with pathogenic m.os on nutrients 3. Occupy and block receptors which requirement for attachment of pathogenic bacteria with epithelia 4. Change PH producing unsuitable environment for other pathogenic m.os as : • Vibrio in vagina • Lactobacillus in milk convert cellulose to lactic acid
5. produce some useful materials as vitamin K vitamin B (antioxidant) prevent aging of cells 6. keep stability of temperature of body Micro Micro flora flora may may convert convert to to pathogenic pathogenic m.os m.os under under specific specific ::conditions conditions 1. Successive using of anti-bacterial compound 2. Misplacing to m.os 3. Suppressing of immune system 4. Stress 5. Malnutrition 6. Sudden change to diet 7. Drugs as cortisone , exposing to 2nd bacterial infection 8. Traveling for long distance
To compensate normal flora: • Medical preparation as Lacteal • Yoghurt in human , dogs
3. 3. Physiological Physiological barriers barriers Physiological barriers include temperature, pH, oxygen tension, and many soluble factors. ,Ex
PH of skin and stomach ---The low pH of sweat and gastric secretions prevents growth of bacteria
Some bacteria can overcome acidic PH :as Produce urease enzyme so, 1 - Helicobacter can overcome acidic PH and pylori cause peptic ulcer
2 - Staph. epidermidis
In skin over come acidic PH and cause acne
4. 4. Physical Physical barriers barriers (Mechanical) (Mechanical) 1- Coughing reflex Expel m.o which attached to ciliated mucous membrane with mucus or sputum 2-Diarrhea In food poisoning cases 3- Repeated urination In urinary tract infection , flushing to m.o , pus cells and excess salts which may lead to stone formation
4. 4. Chemical Chemical mediators mediators Non specific humeral ( )mediators
1 - Complement system Once activated complement can lead to
✏ ✏ ✏
increased vascular permeability Recruitment
تجنيد او تطويعof
phagocytic cells
lysis and opsonization of bacteria .
2 - Lysozyme and phospholipase found in tears, saliva and nasal secretions ( all fluid except urine , CSF ) can breakdown the cell wall of bacteria and destabilize bacterial membranes . 3 - Interferon ( α β ) are proteins that can limit virus replication in cells so, prevent m.os to invade other cells , then m.os float in blood and phagocytosed by phagocytic cells 4 - Properdine Activate complement 5 - Collectin Glycoprotein that block the receptors of most of Gm +ve bacteria
5. 5. Inflammatory Inflammatory barriers barriers Tissue damage caused by wounds or by microbial invasion induces a complex sequence of events as: 1. Vasodilatation 2. Leukocytic infiltration 3. Redness 4. Hotness 5. Bain
These events will increase:
The blood supply Acute phase proteins Soluble antimicrobial fluids Phagocytic cells Nutrients to the inflamed area Temperature So, microbial spreading can be stopped.
6. 6. Phagocytic Phagocytic barriers barriers (phagocytosis)
☹ ☹
One of the most effective innate barriers
☹
Phagocytosis is ability of phagocytic cells to :
هام جدا
consider a transitional stage between nonspecific and acquired specific immunity 1. Ingest particulate materials , pathogen through receptors in their surfaces 2. Digest these substances within lysosome 3. Processing and presentation Ag determinants (epitopes or finger prints) to the T helper to initiate the specific immune response 4. Repair damage by destroying and absorbing of dead materials
Phagocytic Phagocyticcells cells Microphages
Granulated multi nucleated
1. Neutrophil 2. Eosinophil 3. Basophil The largest nucleated cell of blood which developed into macrophages when migrate to tissues
Monocytes
Mono nucleated
After migration of monocytes from blood to tissue become macrophages
Macrophages
Mono nucleated
B- lymphocytes Denderitic cells
â˜ť Body produce 3.7 x 10
11
monoblast /day in the B.M which
still in blood for: 10 -12 hours
3 - 5 days
In presence of IFN- and IL - 2 in high concentration
In presence of IFN- and IL- 4 in high concentration
turn to monocytes
turn in to denderitic cells
Then migrate to tissue
Classification of Phagocytic cells Poly-morphonuclear cells 1-According to cell morphology
Mono-morphonuclear cells
granulated cells 2-According to cytoplasmic granulation
3-According to life span
non granulated
short-life span long-life span
Neutrophils Basophils Eosinophils Monocytes macrophages B cells Denderitic cells Neutrophils Basophils Eosinophils Monocytes macrophages B cells Denderitic cells Neutrophils Macrophages Denderitic cells
4-According to inflammati on type
5-According to their distributio n 6-According to their function
Acute inflammation macrophages Chronic inflammation macrophages
Free or wondering cells --circulate in the blood Resident(Fixed) cells they harbor in the organs Professional Non professional
Organs or tissues
Neutrophils monocytes tissue macrophages neutrophil monoicytes
Examples in table ➊ The difference between them in table ➋
➊ ➊Table Table Name of the phagocytic cells
Connective tissues
Histiocytes
Bone
Osteoclast
Serous cavities
Pleural and peritoneal macrophages
Spleen
Langerhans cells
Liver
Von Kupffer cells
Lung
Alveolar macrophages
Kidney
Mesengeal macrophages
Brain
Microglial macrophages
Lymph nodes
Interdigitating macrophages
Synovial fluids
Synovial A cells
Skin
Langerhans and histiocytes(Malbigian cells)
➋ ➋ Table Table ➋ 1- Localization
2- Receptors 3- Opsonization
هام جدا
Professional
non professional
Lymphatic tissues
Connective tissues and organs
Complement: C3b , C3d Immunoglobulins: IgG , IgE
Non-specific receptors
++++
-
4- MHC class
MHC-I and II
MHC-I
5- Adherence
Adherent
Not adherent
6- Lysosomes
++++
+
++++ Contain alkaline phosphatase
+
8- phagocytosis
++++
+
9- Ag presentation
++++
+
10- Lymphocyte interaction
++++
++
7- Lysozyme secretion
Events of of Events phagocytosis phagocytosis 1- Chemotaxis macrophages attract to the site of infection 2- Adherence or attachment microorganisms are attached to specific and nonspecific receptors on macrophages surface. This binding depends on size and nature of the particles. N.B
Phagocytic receptors
11- Fc Fc receptors receptors Bacteria + IgG (have the Fc regionon their surface )can bind to the receptor on phagocytes . 22- Complement Complement receptors receptors Phagocytic cells have a receptor for the 3rd component of complement, C3b . 33- Other Other Scavenger receptors receptors Toll-like receptors receptors 3- Ingestion (phagosome formation)
â˜ťthe plasma membrane of phagocyte gradually surround m.o
â˜ť The cytoskeleton in the phagocyte is reorganized,
helping to facilitate the extension of the membrane around the particles
â˜ť each receptor sequently interacting with a binding site much like the operation of zipper
4- Digestion and killing (phagolysosomes) Once phagosomes formed, they directed to the perinuclear area where they fuse to lysosome to form secondary phagosomes, phagolysosomes. Within the phagolysomes, the microbes get killed and then digested at acidic pH and by more than 40 enzymes within the lysosomes. phagosomes phagosomes
+
lysosome lysosome
the themicrobes microbesget getkilled killedand andthen thendigested digested
phagolysosomes phagolysosomes acidic pH Lysosomal enzymes
5- Mechanism of killing Respiratory burst associated with phagocytosis leads to increase in the oxygen consumption and activation of oxidases. These oxidases reduce molecular oxygen to superoxides, hydrogen peroxide that form hydroxyl radical and singlet oxygen that have a very powerful antimicrobial effect and inhibit the microbial growth.
o2↑
oxidase (reduction)
Superoxides ) ( O -2 +
hydroxyl radical
hydrogen peroxide
singlet oxygen
H2O2 that have a very powerful antimicrobial effect and inhibit the microbial growth.
Phagoso lysosome
me
Phagolysosome
Events associated with phagocytosis and microbial killing 1- Increase in phagocytic cell size A- Morphological and phenotypic changes
2- Increase in the number of cell organelles including lysosomes and mitochomderia 3- Increase in Fc and C3b receptors. receptors 4- Zippering of cell receptors and increase the membrane fluidity 1- Increase cell phagocytic capacity
B- Functional changes Ů?C- Biochemical changes
2- Increase in the lysosomes hydrolytic enzymes 3- Increase responsiveness to lymphocyte activation 1- Increase in the glucose and ATP production 2- Oxidative burst formation 3- Acid pH
Complementsystem system Complement • Definition
Is a group of complex plasma protein play important role in non specific humoral immunity to overcome microbial infection ( bacteria , virus , parasites , fungus )
• Characters
1. Formed from glycoproteins composed mainly by liver hepatocytes also by blood monocytes, tissue macrophages, and epithelial cells of the gastrointestinal and genitourinary tracts. 2. These components constitute 5% of the serum globulin and 20 % of total plasma protein 3. Its production during foetal life varies with species 4. It doesn’t transfer through placenta 5. Present in serum , body fluids except CSF and urine 6. Present in a very high concentration in Guinea pig’s 7. serum and plasma (fresh serum of Guinea pig is always the source of it in the laboratory work 8. Thermolabile and easily destroyed by heating at 56 o C for 30 minutes or for 1-2 hours at room temperature 9. It preserved by freezing at -20 oc or lypholyzation (freeze drying) but its better to be used fresh and can stored at 4 oc 10. Circulate in the serum in inactive forms as proenzymes, or zymogens, which are inactive until proteolytic cleavage, which removes an inhibitory fragment and exposes the active site.
11. Complement is a fast-acting, cascading system, with most effects occurring within a few minutes 12. Complement composed of at least 30 fraction either named fractions or inhibitors of complement 13. Complement components are designated by numeralsاعداد (C1–C9) , by letter symbols (e.g., factor D), or by trivialعادي names (e.g., homologous restriction factor) . 14. Most of the complement fractions have cell receptors on immune cells and other somatic cells 15. Complement formation is independent on Ag stimulation i.e. doesn’t increased in amount by immunization 16. If concentration of complements is increased than normal needs it lead to adverse condition , out control , act against host it self 17. Complement have 2 fragment • Small “ a ” • Large “ b” Large fragment ( b ) is the active portion , except C2 the large and active fragment is (a) C3 or C4 a
•N.B
b
C2 a
b
Some microbes can overcome normal pathway of complement By production of pseudoimmune mediators : stimulation of complement like substances to keep its level normal but not active immunologically ⇨ not detected by lymphocytes The most immunoglobulin activator for complement is IgM If add distilled water to complement ➙ because it is lacked in ions Ca ++ , Mg ++
-ve reaction
Function
C 5b - 9
Cell lysis : irreversible damage to cell membrane called membrane attack complex ( MAC )
C 3a , 5a
1. 2. 3. 4. 5. 6.
C 3b , 5b
Have opsonization effect i.e. promote phagocytosis and Ag-Ab adherence by serving as an attachment sites for WBCs , platelets that have receptors for it
C 3a , 5b
Chemotactants :attract leukocytes that in turn release lysosomal enzymes and may cause tissue damages
Anaphylaxis : hypersensitivity (allergic reaction) Releasing of histamine after degranulation of mast cell Degranulation of eosinophils Increase of vascular permeability and vasodilatation Aggregation of platelets Promoting inflammatory responsibly acting on mast cells , polymorphnuclear cells , smooth muscles
Environment needed for action of complement system
1. 2. 3. 4. 5. 6.
Ca ions in the first step of activation Mg ions in the second step of activation Ionic strength of the media PH = 7.2 Temperature between 30 - 37 oc Activators as : Ag-Ab complexes Many strain of gram negative bacteria and its lypopolysaccharides in cell wall Many strain of gram positive bacteria and teichoic acid in its cell wall Fungal and yeast cell wall (zymosan) Viruses and virus infected cells Parasites as trypanosomes Aggregation of IgM , IgG, and IgA Cobra venom factor Insect bite N.B, people whose live in desert exposed to snake or scorpion biting have high titre of complement in their serum blood than other people
Mechanism of complement activation A – Classical pathway Ca ++
Ag –– Ab Ab ➊ Ag
➋
C
Ag Ag –– Ab Ab CC 1q1qrrss
1qrs
Mg ++
Ag Ag –– Ab Ab CC 11q r s
qrs
C
Ag Ag –– Ab Ab CC 11q r s CC 44 qrs
4
+
Ag Ag –– Ab Ab CC 11q r s CC44b
Ag –– Ab Ab CC 11q r s CC44 ➌ Ag qrs
qrs
b
CC44 a
a
Make other biological function
➍ Ag Ag –– Ab Ab CC 11q r s CC 44b qrs
b
+
+
CC 44 CC22 b a
CC 22
b
a
CC 22 b
b
C 3 convertase C 3 convertase
➎ CC 33
+
CC33 b
b
CC33 a
a
Found in high concentration so precipitate on surface of m.o
Call ييستدعي
➏ CC 33bb
CC55
& CC 66
activate
CC5566
CC 55 667788 b b
➐
CC 55 667788 b b
Call
CC 99
CC77
activate CC 88
Precipitate on m.o
CC 55 66778899 b b
10 : 20 of it is polymerase
Membrane attack complex (MAC)
Cell Cellwall walllysis lysis • • Release cytoblasmic components Release cytoblasmic components • • Disturbance of salt concentration Disturbance of salt concentration • • Penetrating and entrance of proteolytic enzymes Penetrating and entrance of proteolytic enzymes
B – Alternative pathway Initiators Initiators bacterial endotoxins snake venom insect bitting Prescence of aggregates of IgG , IgA Bacterial lipopolysaccharides
Activate or spontaneously activated
CC 33
CC 33 b b Properdin
CC 33 b b
CC 33 b b
+
CC 33 b b
+
CC 33 a a
In high concentration
CC 33 b BB bb b
Factor Factor BB
C3-convertase
CC 33 b BB bb b
Factor D
For For amplification amplification ييزوده ييزوده
بكمياتC 3 b يتبقي كبيرة
CC 33 b b
Then Then the the same same biological biological mechanism mechanism as as in in classical classical passway passway
C – Lectin pathway
CC 44
+
activate
Lectin Lectin binding binding protein protein
MAC MAC
CC 33
CC 22
CC 44 CC 22 C 3 convertase
In high concentration
هام جدا
A- Classical pathway
B- Alternative pathway
C- Lectin pathway
Specific immunity
Non - specific immunity
Main player C3
Main player C3
Co-players : • C1, C2 , and C4, • Ca , Mg ions
Co-players • Properdin • Factor B • Factor D • Factor H
C3 convertase C4bC2a
C3 convertase C 3b B b
C3 convertase C 4C 2
Activators 1. Immune reaction (Ag – Ab reaction) 2. IgM and certain subclasses of IgG (human IgG1, IgG2, and IgG3)
Activators 1.Bacterial endotoxins 2.Bacterial lipopolysaccharides 3.Snake venom 4.Insect bitting 5.Prescence of aggregates of IgG , IgA
Activator Prescence of “lectin binding protein “ on bacterial , fungal cell wall as in : • Myobacteria • Actinomyces • Some protozoa as trypanosomes
المساعديين
Main player C 3 :
Co-players : • C 2 and C 4
+
s
q
C 1 qrs
r
ٍSpecific immune response
Immunogenicity (antigenicity )
Ag • Certain substances induce detectable immune response when introduced into host • Any substance which react with Ab called Ag .. whether it is Abproducer or not • it called immunogenes (specifically) or antigen (generally) This Ag may be (2) Polysaccharide or synthetic polypeptides
(1) protein
The most potent
Immunogenic under appropriate condition
(4) Pure nucleic acid
(3) lipid
Not antigenic but become Ag when complexed with protein or polysaccharides
Not shown to be Ag
Ag also may be (1) particulate
(2) soluble
Bacteria , virus , …… large protein Polysaccharide molecules Egg white Snake venom
Soluble tissue constituent of animal and plant
•The immune response may be (1) Humoral
(2) cellular
(3) both
Ab production
Mediated by T-cell
Most common
Ag determinant sites (ADS ) ( finger print ) (epitopes ) • Although Ag is macro molecule with high molecular weight , but the immunologically function part of Ag called epitopes • very small sized portion (200 -700 ) Ao (square angestrom) • They may be repeated part of molecules – e.g ⇨ egg albumin
• Their numbers , structure , location are of value in determining the type , intensity of immune response • Each determinant site = 10 – 15 A.A • Every 5000 D on the peptide chain have one determinant site Ag
Ab
Have multiple determinant sites ( multi specific multi valent )
Have 2 similar reaction sites on each end (mono specific bivalent paratope) paratope : the part of an antibody that recognizes the epitope
Ag
Epitopes
Ag
Ag
Ab
Monogenous binding of bivalent Ab to 2 determinant sites on an Ag particles
Hapten • Small material of low molecular weight which can’t induce immune response by itself .. but conjugate with carrier to induce immune response E.x ⇨ penicillin : no immune response – But , penicillin + Albumin (cell protein ) ➙ ⇧molecular weight ➙ immune response
Factors determining Antigenicity ( requirements to be Antigenic ) 1- Foreignness
Ag must be foreign (non-self ) to the body where immune system don’t respond to its self Ag E.x ⇨ Albumin isolated from rabbit serum injected into same or other rabbit won't generate formation of Ab
2- Molecular weight
The higher molecular weight the more antigenic Macromolecular protein (> 10 000 ) Dalton is potent Ag
3- Molecular surface
• The large molecular surface the more antigenic • Charcoal or aluminum hydroxide non Ag due to low molecular surface .. Become Ag when absorbed into inert particles due to display of significant groups on surface
4- Rigidity
• Hydrocarbon posses a large molecular weight and large surface but it can’t act as Ag due to loss of rigidity
5-Chemical complexity
• The more complexity the more antigenic as synthetic poly peptides • Virus ⇨ more complex ⇨ high immunogenic homo polymers Composed of repeated 1 or 2 A.A weak Ag
Co ploymers Composed of different A.A Strong Ag
• So.. Lipid , carbohydrate , nucleic acid ➙ are mono amino acid polymers ➙ poor antigenic • While addition of aromatic A.A ( tryptophan , tyrosine ) ➙ increase immunogenicity
Immunoglobulin (Ig) ( Specific humoral immunity( All immunoglobulin are Ab but not all Ab is immunoglobulin Characters of humoral immunity • React only with Ag that induce its production • But some Ab has cross reaction : can interact with more than 1 Ag as :
1- Specific in action
– HCV X Schistosoma⇨ false result (PCR recommended ) – HCV X Protein 3 of Influenza V. (PCR recommended ) – Flariasis X Entamoeba histolytica (isolation of m.o recommended )
2- Clonal expansio n
Reexposure by the same m.o : Immune cells respond rapidly ⇨proliferate⇨differentiate and divided ⇨form a clone of cells (group of daughter cells from one mother only )
3Formatio n of memory response
By second exposure to infection ⇨ Ig has ability to rapid proliferation ⇨ magnitude the immune response
Specific characters of Ig 1. Produced only by lymphocytes in spleen , liver , lymphnodes , lymphoid associated tissues 2. The main Ig secreted cells are • plasma cells (Produce 93 % ) of Ig • B – cells ( produce the rest 7 % of Ig ) 3. Has ability to fold and re-fold Ag ال تتحور علي شكل 4. Present in all body fluid except CSF & urine 5. Its concentration in body decrease respectively as follow: • Blood (serum +plasma) • Milk , seminal fluid • Vaginal mucous (in certain condition ) • Urine & extracellular fluid in pathogenic condition as cancer of plasma cells in B.M (myloma ) 6. Ig constitute 20 % of serum protein 7. Is part of ૪- globulin fraction of serum protein
1.
Albumin produced mainly by liver
2.
૪- globulin secreted only from Lymphocyte
3.
Concentration of ૪- globulin different due to exposure to infection , immunization
8. Heat resistant except IgE : heated in W.b at 65 oc ➙ no coagulation
Structure of immunoglobulins 1) Normal shape of Ig in inactive stage ( no m.o / no infection ) is T-shape and inactive stage Y-shape 2) Molecular weight 150 KD 3) Consist of 4 poly peptide chains according to molecular weight
Heavy chain
Light chain
4400 A.A
220
A.A
55 – 60 KD
25 KD
5 types according to Ag determinant
2 types :
IgG
IgA
IgM
IgE
IgD
Kappa
Lambada
૪
α
μ
ε
δ
ĸ
λ NH2 nitrogen (amino )terminal
FAB fragment of( )Ag binding
FC fragment of( )crystallization
)CooH (carboxyl terminal
4) Two chain bond with each other by disulphide ponds S=S (covalent inter chain bond ) which held 2 heavy chain with each others and 2 light chain with heavy chains it rich in sulpher A.A (cystine , cystein , valin , methylin ,…. ) which stretch it self (fold & re-fold )
5) Each chain consists of :
variable region
constant region
Which contain high varieties of A.A
Few degree of variability
FAb
Hinge regionمنطقة المفصلة • Area between constant and variable region • Highly flexible • Sensitive to enzymatic and chemical action
FC
1- Fragment of Ag binding
1- Fragment of crystallization
2-Present to ward amino terminal
2- Present to ward carboxyl terminal
3- Contain variable region and part of constant region
3- Contain the rest part of constant region
4- For specific binding to Ag
4- Biological function of FC portion of Ig هام
Ag FAb Fc portion
APC
epitoprs MHC
IgG 1. The only pass through placenta Ab 2. Complement fixation 3. Bind to macrophage 4. Opsonization IgE 1. Bind to mast cells initiate hyper sensitivity reaction (vasodilatation , produce active serotonin , histamine , broncho - constrictor )
Classification of Ig I – According to chemical structures of heavy chain ( amino acid sequence ) G
A
M
E
D
هام جدا
[1] • • • • • • • •
IgG
Represent about 75 % of total Ig Molecular wt. = 150-180 KD Formed from 6 constant region , 4 variable region Main Ig in secondary infection appear after IgM Persist for larger time , its life span 23 days The only Ig which pass placenta (source of defense in newly born ) Monovalent So not effective in acute infection Function : 1. Act against viruses , bacteria , toxin 2. Lysis to m.o 3. Neutralize Ag 4. Opsonization : Mycobacterium , Leptospira , Niseria ⇨ agglutination ⇨hider its movement so be easy to catch by phagocyte 5. FC portion bind with complement and to receptors of phagocytic cells
[2] • • • • • • • • • •
IgM
Represent about 5-10 % of total Ig Highest molecular wt. = 400 KD Life span =5 day Largest , heaviest Ig Star shape , pentomere , composed of 5 basic units which joint to gather by J-chain so , can attach to 10 m.o Appear in primary infection but not persist for long period Have a very strong receptors for complement fixation due to high complicacy of it Most agglutinable Ag Neutralization capacity is low in comparing with IgG Present in high concentration in blood but in very low concentration in other body fluid J- chain
[3] • • • • • • • • • • •
IgA
Represent about 20 % of total Ig Molecular wt. = 150 -300 KD Monomer form Predominant Ig in mucosal surface , external secretion (saliva , tears , sweat , urine ) Most advantage : trapping Ag with mucous layer ⇨ preventing its absorption ⇨ Stimulate of more army of immune syste High binding capacity to pathogens Only Ig secreted in milk so give protection of newly born Its production is mainly due to local stimulation (not affect by increase serum IgA ) No complement fixation but activate alternative pathway Vaccine must stimulate IgA as natural immunity Less Biologically active than other Ig
[4]
IgD
• Binding to receptors on B-lymphocytes in inactive form • Its specific role in immunity still unknown
[5]
IgE
• Highly predominant in hypersensitivity & parasitic manifestation binding to mast cells • Naturally = 0.003 mg/ml blood , in infection reach 1 mg
II – According to Ig function properties As toxoid of Tetanus 1- Toxin neutralizing Ab
2- complement fixation to receptors on phagocytes
IgG
IgA
IgD
75 %
20 %
0.3 %
IgE 0.003 %
Activation of C5 insertion of cell wall of bacterial cel l⇨ C8 ⇨ C9 ⇨ polymerization ⇨ cell lysis IgM
>
IgG
> IgA
3- lysis to bacterial cells
Mainly IgG
4- Agglutination Ab (Agglutinin )
Agglutinate m.o to prevent their movement to be easily phagocytosed IgM > IgA > IgG
Classification of Ig I – According to chemical structures (amino acid sequence ) of heavy chain G
Heavy ch. Produced in M.wt Conc. in serum
M
A
D
E
IgG
IgM
IgA
IgD
IgE
૪
μ
α
δ
ε
150-180 KD
400 KD Largest one
150-300 KD
75 %
5 -10 %
20 %
0.003 mg/ml bl.
40 mg/ kbwt /day
Main Ig in 2ndry infection
Main Ig in primary infection
Main Ig in mucosal surface
Bind to Blymphocyt e
In hypersensit ivity & parasitic manifestati on
Monomer
Pentamer Star shape
Monomer or dimer
Monomer
Monomer
++
Very power full +++
Can’t
Unknown function
-
Memory response
Main Ig
+
+
+
+
Placental barriers
Only pass
-
-
-
-
+ Low
+++
++
-
-
-
+
In Secretory IgA
-
-
Role in infection Basic unit Fixation of complemen t
Agglutinatin g capacity J-chain
ييتحد مع ميكروب واحد
Primary immune response Characterized by : 1.
Secretion of IgM
2.
Take long time
3.
Decline rapidly
4.
Magnitution of Ig is limited
5.
IL -2 5 6 activate division of B-lymphocyte ⇨ proliferation , differentiate give plasma cells , memory cells
Ig concentration
IgM
period M.O Bacteria , virus , parasite
• Macrophage • DC • Monocyte
T-cells ,proliferation differentiation
• Neutrophil
days 5 - 3
Formation of finger print of causative agents then presentation of Ag to T-cells
days 7-15
Then decline at 21 days
Secondary exposure to same infective agent ( secondary immune response ) ( memory response )
Characterized by : • • •
• • • •
Very high production of Ab than in primary immune response Rapid response due to memory cells Secretion of IgG (generalized infection )
Persist for long time , at least 6 months (long lasting immunity ) Highly effective Neutralize microbial toxins or occupy its receptors Plasma cells , memory cells in blood and l.n
IgG
period m6
So , In vaccination must give booster dose after 21 day because immunity decline after 21 day from booster dose , so must stimulate immune cells , memory
Mucosal immunity ( External surface immunity ) ( Secretory immunity ) (Secretory IgA ) Distribution of Ig in external , internal cavities ( surfaces ) : Mucosal immunity protect mucosal surfaces of RT , GIT , UGT , mammary gland ) which are in direct with the external environment ( a major site of Ag exposure ) IgA was the predominant Ig of external secretion IgA : IgG = 5 :1 in mucosal surface External surface 1. Mucous membrane
Internal fluid
Blood ( Serum , plasma(
2. Nasal fluid 3. Milk IgA
( % 75 )
IgG 10-15) (%
IgM IgE ( % 1.5) IgD ( % 1) ( % 1)
Ig concentration
Ig concentration
( % 80 )
IgG IgA
( % 15 )
IgM IgE ( % 10) IgD ( % 3) 0.003) (%
Ab at mucosal surface produced by plasma cell (present in lamina propria of secretory sites such as : gut , respiratory , nasal mucosa , salivary gland )
Mechanism of IgA secretion from mucosal surfaces M-cells :
Mechanism of action in mucosa
– Phagocytic cells – modified epithelial cells – Micro folded epithelial cells – Non- ciliated – Play a very important role in initial immune response on mucosal surface
Ig Ig A A
Mucosal Mucosal immunity immunity Basement membrane
Sub mucosa
➑
➒
Ag
lymph vessels
الجزء الكبر منه يينتقل الي intracellular space
➏ ➊
Blood vessels
➐
Ab Ab
Ig A
ييخرح لل mucosal lumina 3 وييعمل وظائف
هام جدا
Mcell
plasma cells
Memory cells
➋ M-cell
differentiation
➎
Cilia
Phagosome proliferation
Epithelial cells B Macrophage
➍ ➌
Th IL-1
IL-2
1. Trapping of m.o by M-cells ➙ forming phagosome 2. Processing of Ag by M-cells or Macrophage (present in sub mucosal in abundant amount )
3. Presenting of Ag determinants ➙ releasing IL1 ➙ activate Thelper which attached to macrophages ➙ activate IL2 4. IL-2 activation of B-lymphocyte ➙ proliferate then differentiate to give plasma , memory cells 5. Plasma cells produce Ab 6. Ig transport from mucosa to sub-mucosa reach blood and lymph ➙ systemic circulation 7. But , the large amount of IgA absorbed in mucosal surface as follow : 1. 2.
IgA synthesize a secretory component which attach to receptors on basement membrane So IgA accumulate in intracellular space then passed to mucosal surface and the lumina
• Importance of secretory components : 1. 2.
Facilitate transcellular transportation of IgA from submucosa to mucosal lumina Protect IgA from digested by proteolytic enzymes
• Role of IgA 1. 2. 3.
Occupy binding sites of m.o and prevent their attachment and colonization on gut surface Neutralize microbial toxins Aggregate and agglutinate
Immunity Immunity
Specific Specific immune immune response response
Non Non specific specific immune immune response response
))Acquired Acquired ((
))Innate Innate((
))Adaptive Adaptive((
))Natural Natural((
Cellular Cellular immunity immunity
Humoral Humoral immunity immunity
Cell Cell (( mediated mediated ))immunity immunity
Ab Ab(( mediated mediated ))immunity immunity
Physical Physical
Chemical Chemical Biological Biological
Cellular Cellular Inflammatory Inflammatory
Physiological Physiological
Humoral Humoral ))(complement (complement
Cell involved in immune response 1. Macrophage 2. Killer and Natural killer 3. Lymphocytes • T-lymphocyte • B-lymphocyte
killer cells , natural killer cell • One of the immune cells • Have large number of receptors (Fc receptors ) which attach with Fc portion of Ab • Have a role in Ab dependent cell mediated cytotoxicity [ ADCC ]
ADCC ADCC Pathogen infected cell
➊
Ab Fc receptors as CD 16
Fc portion of Ab
Killer cell
➋
Condensation of molecule beside membrane
Perforin form pores in target cell membrane
➌
Cell apoptosis
Killer cell
Natural Natural killer killer [[[[ NK NK
هام جدا
1. antibody, such as IgG, bound to the surface of a pathogeninfected cell. 2. An NK cell's Fc receptor recognizes the Fc portion of an Ab 3. activation of NK cells 4. The most common Fc receptor on the surface of an NK Cell is called CD16 5. Once the Fc receptor binds to the Fc region of IgG, the Natural Killer cell releases cytokines such as IFN-γ, and cytotoxic granules containing perforin and granulysin – Perforin :form pores in the terget cells membrane – Granulysin :allow granzymes to enter the target cell ➙ a poptosis
Remember : ● ● ● ●
Cell mediated immunity more efficient than humoral immunity Ab act on cell surface of macro molecule Ab can’t kill m.o , stop it only Ab block foreign bodies receptors
The major histocompatibility complex (MHC) • Is a gene present inside cells and plays an important role in the immune system • Expressed the protein enter the cell on the surface of cells to T cell • This protein may be either Self
–
… peptide fragments from the cell itself
or –
Non self …. as bacteria , virus
Epitopes • Unique structure carried on Ag surface attach to Ab • It is not mutable ( as PAMP ) but short chain 10 a.a • Always associated with MHC to facilitate Ab recognition formed what is called “ Ag peptide MHC complex ” Ag peptide -MHC complex
• Complex between Ag and immune response • It is a transient stage between non specific ( preparatory stage ) and specific (cell mediated immunity ) • If formed from 18 a.a … attached to MHC II call B-lymphocyte If Ag formed from 10 a.a … attach to MHC I ..call T-cytotoxic
PAMPs
هام جدا
Pathogen-associated molecular patterns • The molecules associated with groups of pathogens • Don’t undergo mutation .
Gram–ve bacteria
Gram+ve bacteria
Lipopolysaccharide )LPS) (on the bacterial cell membrane )
Peptidoglycan
Viruses
Parasites
Nucleic acid
Oligosaccharide
• These PAMP are recognized by pathogen recognition receptors (PRR ) which present only in immune cells
PRR
هام جدا
Pathogen Recognition Receptors
• Are proteins expressed by cells of the innate immune system to identify PAMPs • They include – TLR's ) Toll-Like Receptors) – CD
14
( Cluster of differentiation 14 )
– CR
3
( Complement receptors 3 )
– FCR – CD11 b – KIR – KAR
• PPR may be soluble as lipid binding protein (LBP) or membranous as (CD14 ) • Lipid A of LPS ( lipo polysaccharide ) of gram –ve bacteria bind with LBP (soluble PPR circulate normally in blood ) then attach to CD14 at the membrane of phagocytic cells give intracellular signal to produce cytokines which has 3 effect : 1. Autocrine : acts on the same type of cell that secretes it. 2. Paracrine : acts on neighboring cells 3. Endocrine : act on other site away from secreted site (as hormones) Lipid A Intracellular signal
Cytokines
LPS LBP CD 14
KAR KIR
effect 3 …
…
FCR Phagocytic cell
… CD 11 b
C3
TLR 4
Macrophages [MΦ ] Trapping to Ag Presentation to Ag Create suitable environment to keep integrity of all immune cells
Antigen presenting cell ( APC ) 1. Macrophages 2. B- Cell 3. D-cell
T-cells • • • •
Small white blood cells which participate in immune defenses Comprise about 60 % of circulating lymphocyte They are processed in thymus , secrete lymphokines Indication (activators) of T-cell : 1. 2. 3. 4.
Intracellular m.o as virus , malaria , leishmania , parasites Carcinogens Delayed hypersensitivity Tissue grafting , cell implantation
• Types of T-cells 1. T- helper • Master of immune system • Have receptors CD2 , CD3 , CD4 • Called helper because they assist other cells of immune system as macrophages , B-cell , TC • Types : 1. T h 0 ( Naive or vergin T-cell ) من قبلAgلم يسبق لها التعرف علي
2. T h 1 3. T h 2
Th1
1- Main APC
2- Cytokines produced
Th2
Macrophage
B - cell
IL 2 IL 3
IL 4 IL 3 IL 6 IL 10 ( in certain limit ) TGF
IFN૪ TGF
3- Recognition of Ag associated Ag with MHC I
Ag associated with MHC II
4- Immune response
Humoral immune response
Cell mediated immune response
N.B CD 28 present ABC attach with CD 3 on T-cells and B 7 attach with Cd 80 on T-cells
T- cytotoxic •
•
Receptors • CD 2 • CD 3 • CD 8 • CD 25 Secretes • Perforin • Granzyme : • IFN
protein in nature help in apoptosis
3. T- regulatory ( suppressors ) •
Receptors • CD 25 • CD 56
specific specific cell cell mediated mediated immunity immunity 1- Recognition of Ag
هام
• N.B , T-cell receptors (TCR ) have different shapes to become complementary to all Ag shapes • MHC I present in ER while MHC II present in cytoplasm • In case of viral infection , intracellular parasites Ag integrated by protosome then translocated to endoplasmic reticulum by carrier protein or chaperon … then viral peptide bind to MHC I in ER then traffic to the surface – Chaperon is protein carriers present on the cell act on : • Modification of protein after translation • Degradation of foreign protein • Transportation of protein from cytoplasm to cell membrane through E.R • In case of bacteria or extracellular parasites the epitopes bind to MHC II in cytoplasm and transmit directly to surface
2- Activation
1. Contact signal • •
binding of Ag peptide ( presented by APC ) with T-cell But it is not enough signal require another signal
2. Secretory signal •
Achieved by interaction 0f CD 28 (on ABC ) with CD 3 (on T-cells ) and B 7 (on ABC ) attach with Cd 80 on T-cells
– Macrophage ( APC ) represent Ag on its surface with MHC molecules and produce IL-1 which stimulate T hcell to attach with Ag by its receptors then produce IL2 , IFN ૪ which activate T-cytotoxic
3- Proliferation – Then stimulation of T-cytotoxic to proliferate to give large number of cells – Then production of IL-10 which stop proliferation 4- Differentiation A. Memory cells ( small cells ) : ➙ circulation l.n , secondary lymphoid organs as spleen B. Effector cell (large cell ) ➙ attack 5- Effector phase 1. Effector cell attach to infected cells 2. Concentration of granzyme molecules of effector cells beside the wall toward the infected cells 3. Produce perforin which make pores in the wall of infected cell lead to tranportation of granzyme molecules from teffector cells to infected cells 4. Granzyme molecues :melting to metochondria of m.o lead to cell apoptosis N.B , Cell mediated immunity is effective in case of viral infection and intracellular parasites
Cell Cell mediated mediated immunity immunity
Ag Ab
IFN ૪ IL-2
APC Th
MHC
Tc
IL-1 Proliferation
Infected cell
effector cell
Cell apoptosis
Differentiation
Large cell
Small cell
”Effector cell“
”Memory cell“
Human response
Increasing of immune cells
Chronic infection as T.B Tc
Immune cells
MŐ“ M.o
Period
Viral infection
Complement , IFN , T-cytotoxic , natural killer
[ The diagram of cell mediated immunity ]
Capsulated bacteria
K-cell , complement , Macrophage Capsulated bacteria ➊ Ag Ab
➌
➋ APC
Circulate again ➍
APC ➎ Then degradation of Ag
Toxicity
Neutralization of toxin directly by blocking its receptors Ab binding toxin , K-cell
How How microbes microbes evade evade or or escape escape from from immune immune response response 1. Prevention of phagocytosis : some m.os have capsule protect them from phagocytosis phagocytosis
Bacillus anthracis Streptococcus pyogens 2. Competing with Fc receptors : hence prevention of opsonization
Staphylococcus aureus 3. Inhibition of binding of lysosomes with phagosomes :
Mycobacterium tuberculosis 4. Escape from phagolysosome to cytoplasm :
Mycobacterium
&
Toxoplasma
5. Resistance of phagolysosome acidic pH
Trypansoma
&
enveloped viruses.
6. Direct penetration of phagocytic cells So phagosome not performed and thus avoid the enzymes , lysozyme action But it used phagocytic cells as a transportation mean to spread infection
Mycoplasma
&
Histoplasma
6. Mutation of their epitopes Epitopes and paratopes have complementary amino acids for each others with different charges to bind with each others If the sequence of amino acids of epitopes changed the Ab can’t attach to the new epitopes
HCV
&
FMD
&
Influenza virus
a.a sequence of HCV (valine , glutamic acid , lysine , …… ) after mutation become (glutamic acid , valine , ……. ) 6. Mimicry
محاكاة
:
Steal host protein and precipitate it around themselves so phagocytic cells can’t recognize it (disguising )تنكر
Leptospira
&
Treponema
6. Create protein like substances similar to host protein :
Streptococcus pyogens Secreate streptolysin A which similar to myocardial protein so, lead to production of component similar to host components
10. Production of Ig like substances
HCV Stimulate hepatocyte to secrete Ig like substances and complement like substances leading to stop the function of immune system to produce Ab 10. Resist lysosyme action
T.B Surrounded by mycolic protein or mycolic acid (producing iron chelating materials 窶ｦ prevent iron absorption
Brucella Surround by lipid layer which protect it from lysosyme action 10. Immunoglobulin idiotype closure : Make closure to Ig idiotope by secreting anti 窶的g idiotope
HCV
&
HBS
Hypersensitivity Hypersensitivity
Type TypeII
Type TypeIIII
Immediate
Delayed
IgE
IgG
Type TypeIII III
IgM
Mechanism Mechanism of of immediate immediate hypersensitivity hypersensitivity
هام
1-first firstexposure exposure [ [synthetization synthetizationstage stage] ] 1Allergen Insect bites , Pollen , Cosmetics , Medications Stimulate B-cells Proliferation & differentiation
Blasma cells
Ig E
Mast cells
IgE
Mast cells Eosinophils Basophils
“Caping“ Bridge formation to attach IgE with each others
2-second secondexposure exposure [ [effector effectorstage stage] ] 2Mast cells or eosinophils or basophils have already receptors to IgE
Allergen
Attach to IgE which already persist on mast (cells (as example
Stimulate mast cells to produce protein kinase
produce
Protein kinase حاجات3 يعمل
1. Increasing Ca metabolism 2. Increasing energy 3. Increasing of cell skeleton
deposition of granules near cell membrane
Degranulation …..The granule release [ 1 ] Chemo attractants
Vaso active amine [ 2]
Prostaglandin [ 3]
Chemo attractants [ 1] possessing chemotaxis
• Leukotrin B • PAF “ Platelet activating factors “ • IL 1 & IL 8 1. Attraction of more immune cells to site of allergy 2. Stabilization of allergin through microthrombi ( stabilize
تثبت
it to site of inflammation don’t return )
Vaso active amine [ 2]
• Histamine • Serotonin 1. Vasodilatation 2. Recruitment of more cells 3. Increased mucous secretions Prostaglandin [ 3] End result of allergy 1. Vasoconstriction of blood vessels 2. Spasm of smooth muscle ( hypotension )
Treatmentand andcontrol controlof ofallergy allergy Treatment 1. Avoid the cause 2. Epinepherin (adrenalin ) : to decrease Ca+ exit from cells 3. Anti-histaminic drugs : as Allergin 4. Corticosteroids which acting mainly on mast cells ‌ cause immunosuppresion
N.B N.B Cheotaxis: : Cheotaxis
Directedmigration migrationof ofcells cellsto tosite siteofof Directed infection infection Chemokinase: : Random Randommigration migrationofofcells cellsfrom from Chemokinase bloodvessels vessels blood
Hypersensitivityalso alsoclassified classifiedaccording accordingto tolocation location Hypersensitivity into: : into 1. Anaphylactic Anaphylactic or orsystematic systematic 1. 2. Atopic Atopicor orlocal local: : 2. Contactdermatitis dermatitis •• Contact Conjunctivitis •• Conjunctivitis هام
Immediate Hypersensitivity
Delayed Hypersensitivity
Initiation
Start after 2 min. to 2 hrs.
24 -27 hrs
Effector cells
B-lymphocyte Plasma cells Mast cell Eosinophile Basophile
T-cell (T- cytotoxic) Ag stimulate macrophage to produce cytokines which activate T-cells which divide give memory cell which migrate to l.n and site of infection
Main Ig
Mainly IgE Also IgG , IgM
Mainly IgG
Allergen
Non biological origin as:
Biological origin as :
– – – –
symptoms
Insect bite Pollen Cosmetics medications
Redness , skin rash
– Tuberculin – Mallein
Thickness and elevation of skin (over 4 mm ) due to oedema localized at site of Ag
Vaccines
• Its antigenic structure or product isolated from m.o and used to induce either cellular or humoral immune response or both of them together
Characters of successful vaccines [ 1 ] Factors related to immunology :
هام
1. Should induce both cellular and humoral immune response 2. Memory response 3. No mutation 4. Provide immunity for long duration 5. Produce effective response against all antigenic determinants [ 2 ] Factors related to safety : 1. Not incorporated in host genome … no mutation 2. No reversion to virulent strain 3. Not lead to immune suppression 4. Don’t persist 5. Easily to be administrated 6. The vaccinated animals not become carriers ( no shedding of m.o which may affect contact animals ) [ 3 ] also should be cheap , available , suitable to country conditions
Vaccine failure
هام
1. Reversion to virulent strain 2. Incorporated into host genome .. mutation 3. The vaccine preparation may need specific steps as cold storage which have some hazard as cutting of electric current may lead to changes in vaccine prosperities 4. The animal may be infected before vaccination 5. Incorrect dosage 6. Contamination of vaccine during the preparation , recultivation , or during application 7. Immuno comporomized animals
Types of vaccine 1- Killed or inactivated 1- Method of preparation
m.o killed or inactivated either by : 1. Chemicals as 3 % formaline 2. Physical as heating at 60 oc /1 hr. to denaturate the protein
2- Route of injection
I/M
3- Advantages
1. Very safe 2. Economic
4- Dis advantages
1. 2. 3. 4.
Short duration Require more than more dose Induce mainly humoral immunity only No memory response
2- live attenuated vaccine m.o attenuated by :
1- Method of preparation
– direct exposure to ultraviolet rays – Repeated inoculation in unsusceptible host as egg or rabbit for rabies virus – Unsusceptible temperature like brucella then subcultures for 19 times – Cultivation on inhibitory media as media contain bile salts as BCG for T.B – Withdrawal of water ..dryness and desiccation as in rabies
2- Route of injection
I/M
3- Advantages
1. Induce both cellular and humoral immune response 2. Strong memory response 3. Long lasting immunity 4. Not require more than one dose
4- Dis advantages
1. expensive 2. Make integrate with host genome , cause tumor 3. May convert to virulent strain
or
S/C
3- toxoid
1- Method of preparation
Maintaining antigenicity of bacteria but alternate of the toxogenic part by extraction of toxin then attenuated by chemicals as formalin 0.3% ( while bacteria it self attenuated by formalin 3% ) as clostridia tetani
2- Advantages
Most powerful
3- Dis advantages
Very expensive
4- Subunit vaccine [ protective vaccine ] Composed of only one or more of antigenic structures of the m.o that amplified by molecular engineering (by PCR )
1- Method of Then insert in other bacteria like E-coli ⇨ preparation reproduction of E-coli ⇨ breaking down of Ecoli ⇨extraction of DNA ⇨ qualification ⇨ make in doses ⇨ ready for injection 1. Safe 2. Avoid immuno suppressive epitopes 2- Advantages 3. Induce either humoral or cellular immune response according to method of preparation and the amplification of selected Ag
4- Dis advantages
1. 2. 3. 4.
Expensive Require too many doses No memory response Incomplete protein
5-Virus like particle
1- Method of preparation
Advanced technology using virus like particles , genome viral protein ⇨ amplification ⇨ insert in viral host (like vacuole virus ) ⇨ assemble virus like particles Vacuole virus is virus of insects used to not disintegrate with the virus
2- Uses
In highly mutable m.o as influenza Slow grower m.o m.o not grow on routine tissue culture M.o not has susceptible host
3- Advantages
1. Similar to natural inject 2. Very safe 3. Induce both cellular and humoral immune response 4. Induce long memory response 5. Contain immune stimulant epitopes
4- Dis advantages
1. Require more than one dose 2. Expensive
Adjuvant
• Def
It is non immunogenic substances mixed with vaccine to increase efficiency of vaccine
• Mode of action
1. Slow release of the Ag 2. Long exposure of Ag to specific cells or immuno competent cells 3. Induce low degree of inflammation which result in attraction of immune cells (Magnification of immune response )
• Examples
1. Aluminum 2. Aluminum sulphate 3. Products of some m.o as BCG
• Types
1. Complete Freund’s adjuvant Contain mineral oil + BCG ( inactivated and dried mycobacteria ) 2. Incomplete Freund’s adjuvant Contain just mineral oil without BCG
The most important questions • Compare : 1. Innate & acquired immunity 2. Classical & alternative pathway of complement 3. Immediate & delayed hypersensitivity 4. Primary & secondary lymphoid organs • • • • • • • • • • • • • •
Phagocytosis Professional phagocytic cells Short notes on IgG Cell mediated immunity NK Mucosal immunity Mucous as physical barriers Biological barriers Characters of standard vaccine Vaccine failure Immediate hyper sensitivity Biological function of Fc Portion Short notes on PAMPs & PRR Short notes on MAC [ Membrane attack complex of complement , Nk , Cytotoxic cells ] ونشرح واحده منهم