PAGE test to separate the proteins and antisera to detect the exact proteins that are present in the sample. The IEP can detect monoclonal antibodies in excess, such as is seen in multiple myeloma. Patients with multiple myeloma make too many monoclonal antibodies in a disease that is cancerous to the individual. A protein peak in a certain spot will indicate that a given antibody is being made in excess. The Western Blot test is one that is used after protein gel electrophoresis. The PAGE test is done to separate proteins and then the proteins are immobilized on a nitrocellulose membrane. Antibodies and the membrane are mixed together along with a second antibody that is coupled to something that fluoresces, an enzyme, or something that changes color. This identifies particular antigenic proteins by the presence of a color change or fluorescence. Antibodies in general will also activate complement proteins. These complement proteins will opsonize bacteria in order to facilitate phagocytosis, while others will cause gram-negative bacterial cell lysis. The fact that this can happen can be used to detect the presence of certain antibodies in the patient’s serum. Red blood cells can also be used in a related test called the complement fixation test, which can detect antibodies against fungi, intracellular pathogens, and viruses, which cannot easily be cultured. If there is an antibody and antigen mixed together, all of the complement will be fixed and there won’t be enough complement to lyse the RBCs when these are added along with RBC antibodies. If the antibodies are present, the cells won’t lyse but if the antibodies are absent, the cells will lyse. This is how the complement fixation test is performed.
AGGLUTINATION ASSAYS Agglutination tests clump cells together or antigen-coated latex beads together. It can detect antibodies against red blood cells or against bacteria. These are easy to do and are done on a slide or on a microtiter plate, which is an array of wells used to look for agglutination. There can be direct agglutination assays or indirect agglutination assays. Direct assays look at bacterial cells that agglutinate themselves. Indirect assays use 243
