Secondhand Smoke Causes Transplant Rejection

Cigarette smoke believed to suppress enzymes that assist graft survival

(RxWiki News) In a recent study presented by the American Journal of Transplantation, researchers found that mice that were exposed to secondhand smoke (SHS) four weeks before receiving a graft transplant rejected the treatment.

Zhenhua Dai, M.D., Ph.D., of the University of Texas Health Science Center, tested groups of mice to investigate the cause and effect of secondhand cigarette smoke on certain transplant procedures.

Dr. Dai found that SHS negatively affected the graft survival in mice who received the procedure. 

"Secondhand smoke is also bad - stop smoking.  "

By using a log-rank system, Dr. Dai was able to perform survival tests on the graft recipients and found that SHS suppresses enzymes that grafts normally produce to aid their survival.

According to this study, SHS suppresses the production of CD154, a protein that is normally activated in T-cells and that help regulate the immune system while over-stimulating indoleamine 2,3-dioxygenase (IDO), which is an immunoregulatory enzyme often expressed by tumor cells.

While it is uncertain if SHS is the sole cause in the graft rejection, it is now believed that an immunological mechanism plays a role in the survival of surgical transplants, of which SHS hinders.

"Our findings will definitely promote the public awareness of the smoking problem with transplanted patients, which in turn could save their lives by either quitting smoking or avoiding exposure to second hand smoke after transplantation," said Dr. Dai.

The clinical study was lead by Dr. Zhenhua Dai of the Department of Immunology and Microbiology, Center for Biomedical Research, University of Texas Health Science Center, Tyler, TX. The American Journal of Transplantation first published it in November 2011. No financial conflicts were found.