(isohaemagglutinin) n. one of the antibodies occurring naturally in the plasma that cause *agglutination of red blood cells of a different group.
(clumping) n. the sticking together, by serum antibodies called agglutinins, of such microscopic antigenic particles as red blood cells or bacteria so that they form visible clumps. Any substance that stimulates the body to produce an agglutinin is called an agglutinogen. Agglutination is a specific reaction; in the laboratory, sera containing different known agglutinins provide an invaluable means of identifying unknown bacteria. When blood of different groups is mixed, agglutination occurs because serum contains natural antibodies (isoagglutinins) that attack red cells of a foreign group, whether previously encountered or not. This is not the same process as occurs in *blood coagulation.... agglutination
Health Encyclopedia