Irradiating Donor Organ Reduces Rejection

A study has shown that exposing the donor organ to radiation outside the recipient's body just prior to transplantation plus giving the patient bone marrow from the donor prevents immune system attack within the first months following transplantation. The study, conducted by researchers at the University of Pittsburgh Medical Center (UPMC, PA, USA), was presented at the XVIII International Congress of the Transplantation Society in Rome.

In the study, five patients were scheduled to receive intestines as part of an isolated small bowel, liver and small bowel, or multivisceral transplant. While the surgery was getting underway, the donor intestine was exposed for a few minute to a single low dose of radiation. Surgeons then transplanted the organ and also infused the patient with donor bone marrow. None of the patients have had evidence of rejection for up to four months. In contrast, two control patients who received untreated grafts and no bone marrow, experienced rejection in the first few weeks after the procedure.

The researchers used both the irradiation technique and the infusion of donor bone marrow, containing immune system cells, because the results of their animal studies showed that the combination method reduced the incidence of chronic rejection.

In all, 143 patients have received intestinal transplants at UPMC since May 1990. The majority required an intestinal transplant because of short-gut syndrome, the loss of more than 70% of the intestine due to trauma, surgery, or disease. The overall patient survival rate at UPMC at one year is 72%, with a cumulative five-year survival rate of 52%.

Only within the past 10 years, primarily due to the advent of the antirejection drug tacrolimus, has intestinal transplantation been clinically feasible, noted Kareem Abu-Almagd, M.D., associate professor of surgery at UPMC. But because the intestines are laden with immune system cells that serve as a prime target for recipient immune system attack, cocktails of drugs have been only so effective.