CD4 and infection: Since IL-10 can be produced by various effector CD4+ T cell subsets (including Th1, Th2 and Th17 cells), as well as specialised regulatory populations such as Tr1 [19, 20 34–36], we examined the expression of Th1, Th2 and Th17 lineage-associated cytokines in IL-10-producing (GFP+) and IL-10-GFP− CD4+ T cells purified from IL-10-GFP reporter mice on day 7 of infection.