Researchers receive grant to study transplant tolerance

AORN Journal, Feb, 2003

The National Institute of Allergy and Infectious Diseases has awarded researchers from the University of Pittsburgh's Thomas E. Starzl Transplantation Institute $2.3 million to explore whether a special type of immune system cell can help induce immune tolerance in kidney transplantation, according to an Oct 16, 2002, news release from the university. Researchers will try to harness a subset of dendritic cells with unique tolerance-enhancing qualities to determine whether they can be directed to influence the acceptance of transplanted donor kidneys, including those kidneys that are immunologically mismatched to the recipient.

The studies are based on previous research that shows a subpopulation of dendritic cells may play a key role in convincing the immune system to accept a transplanted organ. Further evidence to support this research includes patients who have undergone transplantation and been weaned successfully off all immunosuppression.

The grant was given based on researchers' previous findings. In one study, a pretransplantation infusion of dendritic cell subtypes allowed for prolonged survival in a mouse heart transplantation model and did not require the use of medications to control rejection. Myeloid dendritic cells, however, accelerated the rejection response.

Patients who have undergone transplantation and are not on immunosuppression have fewer of the type of dendritic cells associated with rejection compared to patients who are prone to rejection or rely on medication to maintain the transplanted organ. They also appear to have more of the "good" dendritic cells, according to the researchers.

Dendritic cells are a rare type of white blood cell. They can be found in all tissues and are known for their ability to identify and present antigens to other immune system cells that are programmed to destroy the antigen. They have been thought to prompt only a rejection response until recently; however, the subtype of dendritic cells seems to have the opposite effect by regulating the immune response and determining that a front-line attack against the organ by T cells is unnecessary.

Starzl Transplant Institute Researchers Receive NIH Grant to Develop Promising Cell-based Strategy for Transplant Tolerance (news release, Pittsburgh: University of Pittsburgh Medical Center, Oct 16, 2002)http://www.upmc.edu/newsbureau/ magee/niad_tolerance.htm (accessed 28 Oct 2002).