Cell Subtype Found to Promote Graft Acceptance

A study has shown that a subtype of dendritic cell plays a key role in preventing organ rejection and may be associated with the long-term survival of a transplanted organ without the need for immunosuppressant drugs. The study was conducted by researchers at the University of Pittsburgh School of Medicine (PA, USA) and presented at Transplant 2001 in Chicago. The findings are significant because dendritic cells have been thought to be involved only in promoting the rejection process.

The researchers found that a pre-transplant infusion of lymphoid dendritic cell subtypes derived from tissue such as the spleen allowed for prolonged survival in a mouse heart transplant model, even without the use of drugs to control rejection. In contrast, myeloid dendritic cells accelerated the rejection response. The research team wants to find out if the lymphoid dendritic cells are present in liver and kidney transplant recipients who have been successfully weaned off immunosuppression, in order to better understand the specific immunologic process that occurs in these patients.

Specifically, the team is examining the role of dendritic cells in tolerance as well as key regulatory proteins within the immune system, where small changes in the code may reveal a patient's potential for rejection. "This will provide a road map for clinicians to help identify those for whom immunosuppression can be safely withdrawn, "said Dr. Thomson, professor of surgery and molecular genetics at the University of Pittsburgh School of Medicine.



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