Impact of RLA matching and cyclosporine on long-term survival in transplanted rabbits.

In order to measure the impact on long-term survival of rabbit leukocyte antigen (RLA) matching and the administration of cyclosporine (CSP) in allogeneic marrow transplantation of irradiated adult rabbits, four groups of five rabbits each were studied. Group 1 consisted of RLA-mismatched animals that did not receive CSP following transplant. All five animals died of infectious complications or graft-versus-host disease (GVHD) (median survival 12 days, range 6-20 days). Group 2 consisted of animals that were similarly mismatched but treated with CSP as postgrafting immunosuppression. All animals also died of GVHD or infection but the median survival was extended to 18 days, range 12-27 days. Group 3 consisted of RLA-matched animals that did not receive CSP. Median survival was 65 days, range 27-121 days, and two are still alive at 120 and 121 days after transplant. Three of five animals died of GVHD. The only group of animals to consistently achieve long-term survival was group 4; these animals were RLA matched and were treated with CSP. Five of five animals survived with a median survival of 564 days following transplant, range 220-806 days. All five became complete hematopoietic chimeras as determined by cytogenetic analysis of bone marrow lymphocytes. Thus, long-term survival after allogeneic bone marrow transplantation in the irradiated adult rabbit was achieved and was dependent upon the use of RLA-matched donors and the administration of cyclosporine as GVHD prophylaxis.