Blood type if they can bind to the corresponding antibodies to generate an immune response. Transfusions are further complicated because platelets and white blood cells (WBCs) have their own systems of surface antigens, and sensitization to platelet or WBC antigens can occur as a result of transfusion. For transfusions of plasma, this situation is reversed. Type O plasma, containing both anti-A and anti-B antibodies, can only be given to O recipients. The antibodies will attack the antigens on any other blood type. Conversely, AB plasma can be given to patients of any ABO blood group, because it does not contain any anti-A
Human blood group systems Human blood group systems The term human blood group systems is defined by International Society of Blood Transfusion as systems in the human species where cell-surface antigens—in particular, those on blood cells—are "controlled at a single gene locus or by two or more very closely linked homologous genes with little or no observable recombination between them", and include the common ABO and Rh (Rhesus) antigen systems, as well as many others; thirty-five major human systems are identified as of November 2014. In addition to the ABO and Rh systems, the antigens expressed on blood cell membrane surfaces include 346 red