More recently, T-cell activation in patients with acute GVHD have a CD4 subset imbalance favoring T helper1 (Th1) cells, which secrete type 1 cytokines interleukin (IL)-2, IL-12, interferon (IFN)-γ, and tumor necrosis factor-α [3]–[5]. The gene discussed is IFNG; the disease is acute graft versus host disease.