FASLG and graft versus host disease: The cytolytic function of CD4 T cells is associated with Blimp-1 (PRDM1) and T-bet (TBX21) expression 34, 38 compared to cytotoxic CD4 T cells, which are known to express high levels of granzyme B (GZMB), granzyme A (GZMA) induces cytolysis in a perforin-dependent, but FAS-FASL-independent manner in graft-versus-host disease 39.