AEMCA Practice Exam

What type of antibodies are present in a person with AB blood?

1. A antibodies

2. B antibodies

3. None

4. Rh antibodies

The correct answer is: None

In individuals with AB blood type, the blood carries neither A nor B antibodies. This is because those with AB blood type express both A and B antigens on the surface of their red blood cells, leading to the conclusion that they do not have the corresponding antibodies in their plasma that would react against those antigens. Having A antibodies would mean the person's immune system recognizes type A antigens as foreign, which is not the case for an individual with AB blood. The same logic applies to B antibodies; since both antigen types are present, the body does not produce antibodies against them. Rh antibodies specifically relate to the Rh factor, which is separate from the ABO blood type system. Consequently, the presence of neither A nor B antibodies accurately reflects the immune tolerance in a person with AB blood type.