Name the antigens that determine human blood groups

The ABO system classifies blood into four major blood groups. These blood groups are determined by the presence or absence of two antigens – A and B – on the surface of red blood cells:

*.Group A – only the A antigen is present on red cells (and B antibody in the plasma)

*.Group B – only the B antigen is present on red cells (and A antibody in the plasma)

*.Group AB – has both A and B antigens on red cells (but neither A nor B antibody in the plasma)

*.Group O – has neither A nor B antigens on red cells (but both A and B antibody are in the plasma.

Rhesus blood groups (or the +/- one often notices next to the ABO blood group) are more complicated than the ABO system, but an important part is the D antigen.

*.Rhesus Positive-has the D antigen on the surface of red blood cells

*.Rhesus Negative-does not have D antigen on the surface of red blood cells (has D antibody in the plasma)

The antibodies will agglutinate with the corresponding antigens if they are present within the blood. For group O there shouldn’t be any agglutination within the A or B circles because the red blood cell does not have A or B antigens.