CD4 and infection: Furthermore, although effector T cells have been implicated as targets of Treg suppression early during infection [23], late Treg cell depletion had no impact on the total numbers of conventional CD4+ and CD8+ T cells in the lungs (Figure 5G), or the levels of prototypical effector T cell cytokines (e.g. IL-10, IFN-γ, and TNF) in the BAL fluid (Figure 5H).