In addition to an expansion of Tregs, viral infections were actually reduced in the low-dose IL-2 treated group compared to the control group.24 In this regard, two more studies have been recently completed in chronic GVHD patients.25,26 NayounKim et al.25 gave a chronic GVHD patient daily low-dose IL-2 treatment for 8 weeks followed by an 18 weeks hiatus and a follow-up administration for another 8 weeks, and demonstrated that low-dose IL-2 could induce a 37.3% expansion of Tregs leading to the improved Treg/Th17 ratios. This evidence concerns the gene IL2 and viral infectious disease.