Graft-versus-host disease (GVHD) pathophysiology occurs in a three-step process: The first step involves tissue damage caused due to treatment regimen of chemotherapy and/or irradiation. Inflammatory cytokines like TNF-α, IL-1 and IL-6 are secreted by the damaged tissue. Subsequently, increased expression of MHC antigens results in donor T cell activation.The second step, donor Th1 cell activation, is characterized by secretion of IL-2 and IFNγ. IL-2 activates donor cytotoxic T lymphocytes (CTLs) while IFNγ activates donor NK cells and macrophages...