University of Pittsburgh Scientists Wean Transplant Patients Off Immunosuppressants Using Donor Immune Priming

University of Pittsburgh researchers kept transplant patients off anti-rejection drugs for 3 years using donor-derived cells to prime the immune system.

By: AXL Media

Published: Apr 18, 2026, 4:31 AM EDT

Source: Information for this report was sourced from University of Pittsburgh

A Decades Long Quest for Immunological Tolerance

A medical milestone has been reached at the University of Pittsburgh, where researchers have successfully demonstrated a method to induce long term organ acceptance without the need for chronic medication. For over thirty years, transplant scientists have sought to achieve "tolerance," a state where the body does not attack a foreign organ despite the absence of drugs. Senior author Angus Thomson, a Distinguished Professor of Surgery and Immunology at Pitt, noted that sparing patients from the side effects of immunosuppression—which include kidney damage, metabolic complications, and increased cancer risk—has been the "holy grail" of the field since the era of the late transplant pioneer Dr. Thomas Starzl.

Engineering Dendritic Cells to Educate the Immune System

The "immune priming" therapy involves a sophisticated process of cellular engineering performed weeks before the actual transplant surgery. Researchers first filter white blood cells, known as monocytes, from the living donor’s blood. These cells are then induced in a laboratory setting to become regulatory dendritic cells, or DCregs. These specific cells act as molecular teachers, tasked with instructing the recipient's immune system to distinguish between harmful foreign invaders and the "friendly" cells of the donor organ. By delivering these DCregs to the recipient one week before the operation, the team aimed to preemptively neutralize the body's natural rejection response.

Clinical Trial Results Show Triple the Success of Historical Standards

The early stage trial involved 13 living donor liver transplant recipients who were monitored closely following the infusion of donor cells. One year after surgery, patients were evaluated for immunological signals that would allow for the safe withdrawal of immunosuppressant drugs. Of the eight participants who met the eligibility criteria for withdrawal, four successfully achieved complete removal of the medication. Significantly, three of these patients have remained entirely off immunosuppressants for more than three years. This 37.5 percent success rate among eligible participants is nearly triple the 13 percent rate observed in historical cases where no immune priming was used.