CD4 and infection: Secondly, they suggest that as infections are resolved, calcitriol-supported development of CD4+FoxP3−IL-10+ Tr1 cells and CD4+FoxP3+IL-10−Treg cells may proceed in an ordered sequence to perform slightly different functions, for example attenuating innate and adaptive immune responses by IL-10-dependent and IL-10-independent mechanisms, respectively.