Effects of restoring lethally irradiated mice with anti-Thy 1.2-treated bone marrow: graft-vs-host, host-vs-graft,...

In vitro treatment of A/J mouse bone marrow with anti-Thy 1.2 serum and guinea pig complement (GPC) eliminated its ability to induce graft-vs-host (GVH) mortality in lethally irradiated C57BL/6J x A/F1 (BAF1) mice. The anti-Thy 1.2 and GPC treatment of A/J marrow significantly reduced spleen cell activation by phytohemagglutinin (PHA) but not lipopolysaccharide (LPS) stimulation in A/J mice assayed 6 weeks after lethal irradiation and reconstitution with the treated marrow. However, the anti-Thy 1.2 treatment of A/J bone marrow did not impair the ability of the lethally irradiated, reconstituted, syngeneic mice to reject C57BL/6J skin grafts. We conclude that lymphocytes in bone marrow which are susceptible to inactivation by anti-Thy 1.2 mediate allograft reactions and/or that radioresistant cells which persist in the recipient initiate rejection of allogeneic skin grafts.