Akram Al-Hilali 2012
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Moving
a living tissue or organ from original body to a new living body. Is transplantation a new practice? Practiced for many centuries on plants. Blood transfusion is a transplantation
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To
cover a deficiency To improve product (in plants) To replace an invalid organ. To replace a non-functioning tissue
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Bone
marrow Hemopoietic stem cell Kidney Liver Lung Skin Bone
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ď‚ž Replace
a bone marrow which contained cancer and has been eradicated by pretransplant chemotherapy and radiotherapy (induction) ď‚ž Replace a bone marrow which has been eradicated because it was producing abnormal cells (inherited) ď‚ž Replace the immune system of the patient, which has been eradicated by pre-transplant chemotherapy and radiotherapy, as it had been incompetent. 08/07/14
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In
plants: usually accepted if from same species. In animals and humans the immune system will decide and usually rejects an allogeneic transplant. Autotransplant poses no immunological problem. What is a isotransplant or isograft? What decides persistence or rejection in allotransplant? 08/07/14
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These
are surface markers on tissues of the body (not only leukocytes) that are used by the immune cells to recognize “own” antigens and cells. Called human leukocytes antigens (HLA) because they were first discovered on leukocytes. Mature red cell contain very little, if any, of those antigens. 08/07/14
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Auto-
and iso- grafts have the same HLA, and so will be accepted as self. Allo grafts acceptance depends on compatibility degree between recipient (his/her immune system) and the graft. Whenever we talk about HLA we mean MHC (major histocompatibility complex). However, there is the minor complex, of which we know very little. No testing for the minor complex is available. 08/07/14
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Tolerance
during embryonic life. Tolerance from common organs between 2 non-identical twins (conjoined twins or siamese twins). Tolerance from repeated exposure to the other antigens. Tolerance by giving immune-suppressive drugs. 08/07/14
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Competent
immune cells (T lymphocytes) find an opportunity to multiply in patient’s body, which is almost paralyzed immunologically after the aggressive chemo and radiotherapy. If there are differences between the two from HLA point, especially if they are limited, the donor’s immune cells will start attacking any tissue or organ in recipient’s body. A very serious disease, especially if acute. 08/07/14
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Induction: chemotherapy, with or without total body irradiation. Prophylaxis against graft-versus-host disease (GVHD) Procurement of HSC, if not already frozen. Transplantation day (Day 0) Total care till the time the transplanted HSC implants and starts to produce blood cells. Immune system takes longer to establish Management of acute and chronic GVHD
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In
case of autologous transplantation marrow or PBSC are procured about a week prior to tx and usually stored frozen with preservative(DMSO) In case of allogeneic transplantation marrow or BPSC are procured on the same day of tx or on the preceding day and tx day in case PBSC are collected over 2 days. Any cryopreserved HSC for tx (as in cord blood tx) will be thawed on day of tx. 08/07/14
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Chemo
therapy not given at doses that completely eradicate original marrow and immune system. Being tried for elderly and some advanced conditions. The use of “donor lymphocyte infusion” DLI has helped make this practice more acceptable. What is the effect of DLI? 08/07/14
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Number is not critical but a minimum number is a must. 2X10^6 per kg of recipient. The more the better, up to 5X10^6 In case CD34 are not counted mononuclears (CD34 cells included) should be more Number needed is related to the weight of the recipient, and is measure per kg of patient’s weight. Cord blood stem cells may do the job at a smaller number. They are more viable and versatile. Many centers choose to count mononuclear cells obtained by aphaeresis from peripheral blood, rather than count the CD34+ cells. Stem cells are not usually counted on bone marrows aspirated for transplantation. Volume of aspirated marrow is measured, which is an arbitrary way of checking it. 08/07/14
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Graft vs. leukemia effect This is probably due to difference between graft T lymphocytes and cancer in the minor histocompatibility antigens. It is considered one of the useful effects of BMT content of T lymphocytes. T lymphocytes in the donor’s stem cell harvest are also the main cause of GVHD. This puts the transplant team in a situation where they may not know whether to remove T lymphocytes in the graft or keep them.
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