CD4 and infection: Although a robust IFN-γ response is important for primary and secondary resistance to L. major[38], [39], recent studies suggest that other factors distinct from the magnitude of IFN-γ response might play a more dominant role in regulating the outcome of infection with L. major. For example, despite the presence of strong IFN-γ response, L. major clone SD (MHOM/SN/74/SD) induces chronic non-healing lesions in C7BL/6 mice that is resolved only after blockade of IL-10 or depletion of CD4+CD25+ Tregs [40].