Question

Clumping of RBC may occur when blood of one person is mixed with serum or blood of another person. This is due to
A)Antigen-antibody reaction
B)Antitoxin-antibody reaction
C)Antigen-antigen reaction
D)Antibody-antibody reaction

Answer 1

A blood type (also referred to as a blood group) is a blood group dependent on the presence and lack of antibodies and inherited antigenic compounds on the surface of red blood cells (RBCs). These antigens may be proteins, sugars, glycoproteins, or glycolipids, depending on the blood group scheme.

Complete answer:
There is either antigen A or antigen B in the RBC membrane, or both antigen A and B or no antigen at all, so the blood is graded as blood group A, B, AB and O respectively. Blood plasma group A will have antibodies for B, B will have antibodies for A, AB will have antibodies for A, and O will have all antibodies. This will lead to an antigen-antibody reaction if blood is transfused at random - as if A is the recipient's blood group when the donor's blood group appears to be B, that will lead to RBC clumping.

There is a reaction of agglutination between comparable antigens and antibodies (for example, antigen A agglutinates the antibody A and antigen B agglutinates the antibody B). Transfusion, however, should be considered healthy as long as the recipient's serum does not produce antibodies to the donor's blood cell antigens.

Hence, the correct answer is option (A)

Note: As of 2019, in addition to the ABO and Rh systems, the International Society for Blood Transfusion has established 36 blood group systems. Thus, several other antigens are expressed on the RBC surface membrane in addition to the ABO antigens and Rh antigens.