AN ANALYSIS OF THE INHIBITORY EFFECT OF CORYNEBACTERIUM PARVUM ON GRAFT-VERSUS-HOST DISEASE

Abstract

Graft-versus-host (GVH) disease, initiated by the injection of parental strain (C57BL) spleen cells into adult F1 hybrid mice, is inhibited dramatically by pretreatment of the host with a suspension of killed Corynebacterium parvum. This protective effect is demonstrable in terms of both survival rates and phagocytic responses. By means of the T6 chromosome marker, it was found that proliferation of donor cells in the spleen was largely suppressed. Furthermore, antibody formation by adoptively transferred preimmunized C57BL spleen cells was depressed in C. parvum treated F1 hybrid recipients. The inhibitory effect induced by C. parvum could be attributed neither to augmentation of an immune response against hypothetical parental strain antigens nor to lack of space for donor cells in the host due to gross proliferation of lymphoreticular tissues. Resistance to donor cells in C. parvum-treated F1 hybrids could be overcome either by massive overloading with the donor cells or by 500r whole body irradiation of the host. Evidence is discussed which suggests that C. parvum augments a preexisting low grade resistance to parental cells in the strain combinations used, which may be an expression of the phenomenon of allogeneic inhibition.