Veterinary Immunology and Serology

ABO Blood Groups system

ABO BLOOD GROUP SYSTEM

• The antigen found on the surface red blood cells (RBC) are called blood group antigen.
• The ABO system contains four blood groups and it is determined based on the presence or absence of two distinct antigens.
• RBC of group A carry antigen A, group B carry antigen B, O group have neither A nor B antigen and group AB carry both A and B antigen.
• Group A is subdivided into A1 (about 80%) and A2 (about 20%). The four antigens can be distinguished by two distinct isoantibodies present in the serum.
• ‘A’ groups people have anti B antibody, B groups have anti A antibody, O groups both anti A and anti B antibody, where as AB groups will neither have anti A nor anti B antibodies. When erythrocytes are mixed with serum containing corresponding antibodies, agglutination occurs (table ).
• Isoantibodies appear in the serum by about six months of age and persist thereafter.
• Since O groups do not have either A or B antigen, RBC from this group of people are not agglutinated by serum of any other blood groups, thus O groups are used as universal blood donor. But serum from O group contain both anti A and B antibodies and agglutinate erythrocyte of all other blood groups that means they can receive blood from group O only.
• AB groups do not have anti A or anti B antibodies and used as universal acceptor.