Biology · Ch 10 — Human Health and Diseases
Antigens on Blood Cells: ABO and Rh Blood Groups
Antigens on Blood Cells: ABO and Rh Blood Groups
Antigen on Blood Cells : The surface of human red blood cells (RBCs) carries a number of genetically determined antigens, which give rise to several distinct blood-group systems — ABO, Rh, Duffy, Kidd, Lewis, P, MNS, the Bombay blood group, and others. Two of these systems matter most in everyday clinical practice: ABO and Rh.
ABO Blood Groups : The ABO blood group system was discovered by Karl Landsteiner in 1900, who identified two antigens (agglutinogens) on the RBC surface, named antigen A and antigen B, along with their corresponding antibodies (agglutinins) in the serum, called antibody 'a' and antibody 'b'; the fourth group, AB, was discovered soon after by Landsteiner's students Decastello and Sturli in 1902 (Landsteiner himself later won the Nobel Prize for this discovery). Depending on which antigens are present, a person's blood falls into one of four groups:
Blood group A: Genotype I^A I^A or I^A I^O; Antigen on RBC surface = A; Antibody in serum = Antibody b; Can donate to A, AB; Can receive from A, O.
Blood group B: Genotype I^B I^B or I^B I^O; Antigen on RBC surface = B; Antibody in serum = Antibody a; Can donate to B, AB; Can receive from B, O.
Blood group AB (universal acceptor): Genotype I^A I^B; Antigen on RBC surface = A and B; Antibody in serum = Nil; Can donate to AB; Can receive from A, B, AB, O. …
So group A individuals carry antigen A and antibody b; group B individuals carry antigen B and antibody a; group AB individuals carry both antigens and no antibodies (making them the universal acceptor, since neither antibody is present to react against a donor's antigens); and group O individuals carry neither antigen but both antibodies (making them the universal donor, since their RBCs carry no antigen for a recipient's antibodies to attack). …