Question

When the O group person receives blood from the AB group, agglutination occurs but agglutination does not take place when the AB group person receives blood from the O group why? Give reason.

Answer 1

Hint: AB blood group is also known as a universal acceptor while a person with an ‘O’ blood group is also known as a universal donor. Both antigen ‘A’ and antibody ‘b’ are incompatible and antigen ‘b’ and antibody ‘B’ are incompatible to each other.

Complete answer:
Since the blood group ‘O’ is a universal donor (i.e. can give blood to any other person with any blood group) and not a universal acceptor (can accept blood from any blood group), agglutination (clumping of blood) occurs. When a person with blood group ‘AB’ receives the blood from blood group ‘O’, agglutination does not occur because the person with blood group ‘AB’ is a universal acceptor, and blood group ‘O’ is a universal donor.
A person with an ‘O’ blood group has no antigen on RBC but has ‘a’ and ‘b’ antibodies and can donate blood to anyone. In the case of the ‘AB’ blood group, it has no antibodies in the plasma but has antigen ‘A ‘and ‘B’. So when a person with blood group ‘O’ receives blood from the ‘AB’ blood group, due to antigen-antibody reaction agglutination occurs. A person with an ‘AB’ blood group can give blood only to a person with an ‘AB’ blood group. ‘O’ blood group can receive from a person with an ‘O’ blood group and no one else.

Additional Information:
- The safest blood transfusion is O negative.
- Blood group A has A-antigen and b-antibodies.
- Blood group B has B-antigen and a-antibody.

Note:
Knowledge of blood group is used in safe blood transfusion so that the corpuscles factor the donor’s blood must be compatible with the plasma factor of the recipient’s blood. The antigens are found on the surface of the RBC while the antibodies are found in the blood plasma.