Searching for a Transplant-Tolerance Test

A group of transplant patients who no longer require immunosuppressive drugs are being studied by researchers in the hope of finding clues that could yield simple laboratory tests predictive of transplant tolerance. The researchers are at the University of Pittsburgh's Thomas E. Starzl Transplantation Institute (Pitt, USA), recently awarded a grant by the U.S. Immune Tolerance Network to conduct the study. Transplant tolerance is a key area of study for this network, a US$144 million undertaking supported by a number of U.S. research organizations.

The Pitt team was selected because of its research in transplant immunology, which has resulted in 40 liver transplant recipients in a controlled study who have been weaned off anti-rejection drugs and remained drug-free for a mean of 6.6 years. The new project will enable further study of these patients and others to determine why their transplanted organs continue to be accepted by their immune systems without the aid of drugs, and to identify potential tests that could predict patients with transplant tolerance.

So far, the researchers have focused on the role of dendritic cells in tolerance and are performing genetic analyses of key regulatory proteins within the immune system, where small changes in the code may reveal a patient's potential for rejection. The new funding will enable both areas to be fully explored in order to arrive at a distinct and reliable laboratory profile consistent with the tolerance state.

"Tolerance assays could support a number of clinical trials and might provide important clues to understanding how tolerance impacts autoimmune diseases as well as allergy and asthma,” noted Adriana Zeeve, Ph.D., a professor of pathology and surgery and co-principal investigator.