Identifier for cells
Mhc is a marker on each cell, which tells our immune system whether the cell is our own or "foreign" (an infection or a transplant
), and our body tries to destroy the "foreign" cells.
This is great to get rid of infection, but also why transplants can be rejected. To minimize the risk of rejection, transplant doctors try to find donors with mhc similar to the patient's, often within the family.