ABO blood groups

Specific antigen system located on red blood cells (RBCs) and platelets (e.g. blood type A, B, AB or O). ABO blood type determination is an essential part of pre-transfusion testing for patients. (Note: Patients with type A RBCs will have type B antibody in their plasma, while patients with type B RBCs will have type A antibody in their plasma. Since type O patient's red blood cells lack A antigen and B antigen, then not surprisingly they could have antibodies to both A and B antigens in their plasma. On the other hand, AB patients plasma is typically devoid of antibodies to either A or B antigen. Hence, the universal donor for RBCs is type O (devoid of A or B antigen) and universal donor for plasma is type AB (devoid of anti-A or Anti-B anti antibodies).