Question

Why might different MHC I molecules between donor and recipient cells lead to rejection of a transplanted organ or tissue?

a) MHC I molecules are not involved in immune responses.
b) Different MHC I molecules signal compatibility and prevent rejection.
c) Mismatched MHC I molecules trigger an immune response, leading to rejection.
d) MHC I molecules have no role in transplant compatibility.

Answer 1

Mismatched MHC I molecules between donor and recipient can trigger a cytotoxic T cell response, leading to organ or tissue rejection due to the immune system recognizing the transplanted tissue as foreign.

Step-by-step explanation:

Different MHC I molecules between donor and recipient cells can lead to rejection of a transplanted organ or tissue because these molecules are crucial in signaling to the immune system what is self and what is foreign. The mismatched MHC I molecules trigger an immune response, which leads to the rejection of the transplant. When the recipient's immune system detects these foreign MHC I molecules, cytotoxic T cells are activated to attack the transplanted tissue, seeing it as an invader. Despite immunosuppressive drugs and advances in tissue typing, achieving a perfect match is difficult, making some degree of rejection common.