ABO Antigens & Antibodies
Ag on RBCs
Ab in plasma
ABO Blood Type
A
B
A & B
none
anti-B
anti-A, anti-B &
anti-A,B
anti-A
none
A
B
AB
O
Ag = antigen
Ab = antibody
Note: the antibodies are “natural
occurring” – that is they are present in
patients plasma without patients
having been exposed to antigen.