Ketel said, for her, another gratifying aspect of transplant surgery is helping patients during the healing process. After the transplant surgery, patients undergo anti-rejection therapy because the immune system tries to reject the “foreign” organ from the body. “We use immunorepressive drugs to partially block their immune system and avoid rejection of the organ. It’s challenging, yet rewarding, to find the proper balance of anti-rejection drugs without depleting too much of the immune system’s function,” she said.

Extract from :

http://www.uams.edu/info/Updates/April01/organ.htm