CD4 and tuberculosis: Moreover, unlike IFN-γ, CD4+ T cell-mediated production of IL-10 and MIP-1β decreased in a CD8+ T cell-independent manner upon 4-1BB ligation (Fig. 5 B and C), suggesting that in Ag85B-responding CD4+ T cells the regulatory mechanisms controlling secretion of IFN-γ differ compare to those modulating other cytokines influential in TB protection.