Agglutination Process in Transfusion Reactions When bloods are mismatched so that anti-A or anti-B plasma agglutinins are mixed with red blood
cells that contain A or B agglutinogens, respectively, the red cells agglutinate as a result of the
agglutinins‘ attaching themselves to the red blood cells. Because the agglutinins have 2 binding sites
(IgG type) or 10 binding sites (IgM type), a single agglutinin can attach to two or more red blood cells
at the same time, thereby causing the cells to be bound together by the agglutinin. This causes the cells
to clump, which is the process of ―agglutination.‖ Then these clumps plug small blood vessels
throughout the circulatory system. During ensuing hours to days, either physical distortion of the cells
or attack by phagocytic white blood cells destroys the membranes of the agglutinated cells, releasing
hemoglobin into the plasma, which is called ―hemolysis‖ of the red blood cells. these antibodies are
called hemolysins.
