The effect of treatment withrecombinant cytokines, antibodies to cytokines and to cytokinereceptors on the development of GVHD was investigated.Administration of recombinant IL-2 to allogeneically reconstitutedmice strongly increased the morbidity and mortality whereasinjection of IL-1α and TNF-α did not influence survival.Administration of antibodies against IL-2 or the IL-2 receptordecreased the morbidity and mortality. This evidence concerns the gene TNF and graft versus host disease.