Why do killer cells cause rejection of an orgnan transplant?

Killer cells, or cytotoxic T lymphocytes, play a crucial role in the immune response by identifying and destroying cells that are perceived as foreign. During an organ transplant, the recipient's immune system recognizes the donor organ's cells as non-self due to differences in major histocompatibility complex (MHC) molecules. This triggers the activation of killer cells, which attack and destroy the transplanted tissue, leading to organ rejection. Effective immunosuppressive therapies are often necessary to prevent this immune response and ensure the transplant's success.