Question

Graft rejection occurs when

• A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion
• B. Both Assertion and Reason are true but Reason is not correct explanation of Assertion
• C. Assertion is true but Reason is false
• D. Assertion is false but Reason is false

Answer 1

The correct option is A Both Assertion and Reason are true and Reason is the correct explanation of Assertion

MHC is a cluster of proteins displayed on the surface of each and every cell of our body. MHC is unique for a person. Our cells are continuously breaking down old proteins into smaller peptides. These small peptides are held by MHC and displayed on the surface of the cell. If all the peptides displayed are from within the body, the immune system can recognise this cell as self. Any cell displaying a protein fragment that is not from within the body, but of a foreign pathogen, is recognised as non-self. When a human transplant is performed, MHC molecules from a donor are recognised by the recipient's immune system triggering an alloimmune response. Matching of donor and recipient for MHC antigens has been shown to have a significant positive effect on graft acceptance.