IL6R and graft versus host disease: Anti-TNF ameliorates GVHD while preserving GVL effects in experimental murine models.Anti-IL-6R inhibits Th1 and Th17 cells while expanding Tregs, thus preventing GVHD in murine models.Combined blockade of both TNF and IL-6R prevents GVHD but does not impair GVL effects.