One-way occurrence of graft-versus-host disease in bone marrow chimaeras between congenic MRL mice.

Bone marrow cells (BMCs) of MRL/Mp-lpr/lpr (MRL/l) mice, when infused into irradiated MRL/Mp-+/+ (MRL/n) mice, induced graft-versus-host disease (GVHD) and recipients died of wasting syndromes beginning around a few weeks later. Protracted appearance of GVHD was observed when (MRL/n X MRL/l) F1 mice were used as recipients of MRL/l BMSs. On the other hand, MRL/n BMCs did not elicit GVHD in irradiated MRL/l mice. Treatment of MRL/l BMCs with anti-Thy-l antiserum plus complement did not eliminate GVHD-provoking capacity. Thymectomy of the recipents reduced the incidence of GVHD. No apparent reaction was observed in mutual mixed lymphocyte culture of spleen cells from MRL/l and MRL/n mice. These data suggest that injected T cell precursors of MRL/l mice become mature through the host (MRL/n mice) thymus and appear in the periphery as functioning T cells, resulting in the appearance of GVHD.