To assess the clinical effect of low-dose IL-2 therapy, we treated the lethal GVHD preclinical model, in which model B6D2F1 mice were lethally irradiated and transplanted with 5 million spleen cells and 5 million bone marrow cells from B6 mice and then 5000 IU of IL-2 was administered day 5 to day20 (Figure 5A). Here, IL2 is linked to graft versus host disease.