Source: Kelsey Perreault
Cellular markers that play an important role in mediating white blood cell activity. There are many variants of the MHC, and matching the MHCs of organ donor and recipient is an important measure in preventing organ transplant rejection.
Cytotoxic T cells directly carry out the attack on bad, infected or defective cells during adaptive immunity. They attack by secreting proteins that puncture the cell membrane, and then they release lytic enzymes into the cell that cause its internal destruction. This process will eventually induce apoptosis of the damaged cell.