Other reports have demonstrated the ability of Treg cells to produce IFN-γ; for example, IFN-γ-producing Foxp3+ Treg cells are observed in vivo during viral infections and acute graft-versus-host disease in mice, and in patients with multiple sclerosis and type I diabetes mellitus, and in several in vitro studies (Oldenhove et al., 2009; Dominguez-Villar et al., 2011; McClymont et al., 2011; Zhao et al., 2011; Koch et al., 2012; Koenecke et al., 2012). Here, IFNG is linked to viral infectious disease.