<P> Blood donors with exceptionally strong anti-A, anti-B or any atypical blood group antibody may be excluded from blood donation . In general, while the plasma fraction of a blood transfusion may carry donor antibodies not found in the recipient, a significant reaction is unlikely because of dilution . </P> <P> Additionally, red blood cell surface antigens other than A, B and Rh D, might cause adverse reactions and sensitization, 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 . </P> <P> 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 or anti-B antibodies . </P> <P> Typically, blood type tests are performed through addition of a blood sample to a solution containing antibodies corresponding to each antigen . The presence of an antigen on the surface of the blood cells is indicated by agglutination . An alternative system for blood type determination involving no antibodies was developed in 2017 at Imperial College London which makes use of paramagnetic molecularly imprinted polymer nanoparticles with affinity for specific blood antigens . In these tests, rather than agglutination, a positive result is indicated by decolorization as red blood cells which bind to the nanoparticles are pulled toward a magnet and removed from solution . </P>

Why is blood group o called the universal donor