title: Studies of the effects of alloimmunization on the local graft-versus-host reaction in the rat.
abstract: A model of rat graft-versus-host reactivity (GVHR) has been studied using lymphoid cells obtained following i.v. immunization of the parental strain donor with allo- or xenoantigens. Twenty-four hours after immunization with 10(7) F1 hybrid bone marrow cells, spleen cell reactivity inducing GVHR was increased, contrasting with decrease peripheral blood lymphocyte reactivity. This is probably attributable to an alloantigen-induced recruitment of GVH-reactive cells in the spleen. From the 3rd day up to 6 weeks after immunization, spleen cell and peripheral blood lymphocyte GVHR remained low. The suppression was nonspecific and was observed over a wide dose range of allogenic and semiallogeneic lymphoid cells of different origins. Allogeneic red blood cells and platelets were also effective  in inducing suppression, but xenogenic lymphocytes and red blood cells were inefficient. The ability to induce suppression remained after heat killing the immunizing cells for 2 hr at 45 C, but disappeared if they were heated for 30 min at 56 C. In one of the two strain combinations studied, mixing experiments suggest that the suppression observed 1 week after immunization with 10(7) F1 hybrid bone marrow cells, a protocol used to achieve active enhancement of organ allograft, might be attributable in part to a nylon-wool-nonadherent suppressor cell.
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000276:immunology; D016026:Bone Marrow Transplantation; D004306:Dose-Response Relationship, Immunologic; D005260:Female; D006087:Graft vs Host Reaction; D007114:Immunization; D007165:Immunosuppression Therapy; D008214:Lymphocytes / Q000276:immunology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains / Q000276:immunology; D013154:Spleen / Q000276:immunology*; D013997:Time Factors