ORTHOTOPIC BONE TRANSPLANTATION IN MICE

Abstract

Various methods of reducing the immune response to allogeneic bone grafts, either by pretreating the graft or by immunnosuppressing the recipient, were compared. Tibial grafts from B10.D2 mice, either untreated or pretreated in various ways, were transplanted into B10 recipients. The antibody response was followed and the bone healing extent at 4 mo. was assessed. Pretreatment of the graft by X-irradiation, freezing, or by incubation in alloantisera (either anti-H-2 or anti-Ia) reduced or abolished the graft immunogenicity. Immunosuppression of the recipient with methotrexate or antilymphocyte serum (ALS) also greatly depressed the antibody response. When graft healing was assessed, none of these treatments except ALS improved the delayed bone allograft healing. Probably X-irradiation, freezing, alloantiserum pretreatment, and methotrexate all interfered with bone healing directly, whereas ALS did not. Evidently many methods will reduce the immune response to allogeneic bone, but only ALS will improve the allogeneic bone healing. As a corollary to the observation that pretreatment with anti-Ia serum markedly reduced the bone allograft immunogenicity, much of the bone allograft immunogenicity is attributable to an Ia-positive cell population.