CD4 and infection: A recent study by the group of Rosen, looking at end-stage liver disease, did reveal enrichment of CD4+ T cells secreting IL-17 in comparison to blood in 11 patients (Foster et al., 2012), although the nature of the infiltrate at earlier stages of infection remains to be determined, and the co-expression of IL-17 or IL-22 with IFN-γ has yet to be defined.