Why are transplanted organs rejected?

What happens in graft rejection?

The human immune system is designed to attack anything it doesn't recognize.

White blood cells recognize the body's tissues by looking for a set of antigens on the surface of each cell. The most important of these make up the major histocompatibility complex. When your immune system finds cells in your body that don't show the right MHC proteins, it tries to destroy them.

Doctors test the MHC of potential organ donors to find the best match. The test focuses on six important MHC antigens, which can be identified from a long list that includes hundreds of possibilities. The chances of a perfect match are very small. The closer the match, the better the success rate for the transplant. Transplant rejection can also be lessened by use of immunosuppressant drugs after transplant.

Did you know? Identical twins, who share the same MHC profiles, never reject each other's tissues.

Comic idea by Jolhf Mathai Koshy