Question

Graft rejection occurs when

• A. MHC molecules of the donor and recipient do not match
• B. Fingerprint of the donor and recipient do not match
• C. DNA of donor and recipient do not match
• D. All of the above

Answer 1

The correct option is A MHC molecules of the donor and recipient do not match

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.