The role of IL-10 in the immune response to MTb was studied. We have identified that IL-10 plays an early and transient role in the control of the immune response to MTb and now show that this involves enhanced migration of IFNgamma producing CD4+ and CD8+ T cells into the lung rather than enhanced mycobacterial killing. The effects are accompanied by enhanced G-CSF, GM-CSF, TNF, IL-6 and IL-17 levels although the enhanced clearance of bacilli in IL-10 deficient mice we now show is independent of IL-17.