Antiglobulin test (antiglobulintest) was established by Coombs in 1945, so it is also called Coombs test, which is a very useful method to detect incomplete antibodies against red blood cells. In the agglutination reaction, the role of IgM antibodies is hundreds of times greater than that of IgG antibodies, so P ~ IgG antibodies often show incomplete reactions, that is, invisible antigen-antibody reactions. Such antibodies are sometimes called incomplete antibodies. The so-called incomplete antibodies are mostly 7S IgG antibodies, which can firmly bind to the corresponding antigen, but because of their small molecular weight, they cannot play a bridging role, and no visible reaction occurs under normal conditions. Coombs use anti-globulin antibodies as secondary antibodies, linking specific antibodies that bind to antigens on the surface of red blood cells, causing red blood cells to agglutinate. There are two types of methods often used as experiments:
(1) Direct Coombs test
Add the anti-globulin reagent directly to the whole blood of the subject with antibody binding on the surface of red blood cells to see cell agglutination. The legality of slides can be used, and the semi-quantitative analysis can also be done by the test tube method. Commonly used for incomplete antibody detection on red blood cells of patients with neonatal hemolysis, autoimmune hemolysis, idiopathic autoimmune anemia, and iatrogenic hemolytic diseases.
(2) Indirect Coombs test
Used to detect free incomplete antibodies in serum. Combine the test serum with red blood cells with the corresponding antigenicity of the incomplete antibody to be tested. With the addition of anti-globulin antibodies, visible red blood cell agglutination occurs. This test is mostly used to detect maternal Rh (D) antibodies in order to detect and avoid the occurrence of hemolysis in newborns. Blood group antibodies produced by transfusion of incompatible red blood cells can also be detected.
In addition to the Coombs test, which is widely used in the detection of blood diseases, specific anti-globulin serum such as anti-IgG serum, anti-IgA or anti-IgM, and anti-complement serum can be used to analyze the incomplete antibodies bound to red blood cells Immunoglobulin subclasses, etc.
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