1. Antibodies present in the blood serum of one individual that react against the antigens of another individual of the same species; naturally occurring antibodies in blood that cause agglutination of incompatible blood types.
Usage: medical/immunology; plural form; singular is isoagglutinin; also called isohemolysins when they cause hemolysis

Examples

• Isoagglutinins in type O blood react against both A and B antigens on donor red blood cells.
• The presence of isoagglutinins is why blood type compatibility is critical for safe transfusions.
• Isoagglutinins develop naturally without prior exposure to incompatible blood.
• A person with type B blood has isoagglutinins against type A antigens.
• Testing for isoagglutinins is part of the standard blood bank screening process.