Individuals produce different titers of isohemagglutinin? (also called isoagglutinin) An isoantibody normally present in the serum of an individual that causes the agglutination of the red blood cells of another individual of the same species. The typical range observed for anti-A isohemagglutinin titer is 32-2048, while that for anti-B is 8-512. Accordingly, there is no normal titer expected from any particular specimen. Under certain conditions or disease states, an autoimmune response is induced and isohemagglutinin titers increase.
Maternal isohemagglutinins are associated with ABO-hemolytic disease of the newborn. Isohemagglutinin titers are performed in cases of suspected parasitic disease. Parasites such as Toxocara, Ascaris, Schistosoma and Plasmodium express A- and B-like antigens on their surfaces, eliciting increases in anti-A and anti-B isohemagglutinin titers.
This is an assay for the qualitative determination of isohemagglutinin titer in serum. In addition to titering anti-A and anti-B antibodies (i.e., isohemagglutinins), the assay includes a determination of red blood cell type to confirm the isohemagglutinin results..
Blood type determination (front typing) and confirmatory testing by isohemagglutinin titer (back typing) are routinely performed using hemagglutination. Hemagglutination is the process by which red blood cells (RBC) agglutinate in the presence of antibodies to yield a solid pellet. Hemagglutination is assessed by visual observation at four levels, categorized as 1-4: one is slight agglutination represented as a grainy appearance of the sample as cells begin to aggregate; four is a solid mass of agglutinated cells; two and three represent intermediate states of increasing agglutination. Blood typing is performed by hemagglutinating a patient RBC sample with commercial antisera; isohemagglutinin titer is determined by observing the highest dilution of patient serum that results in RBC agglutination.
Isohemagglutinins are typically IgM class antibodies, although type O individuals tend to produce small ammounts of anti-A and anti-B of the IgG class.