It has been demonstrated that cells from IL-10−/− mice produced more NO, IFNγ, and IL-12 compared with cells from BALB/c mice [8] and IL-10−/− mice which become resistant to infection [7] suggesting that IL-10 increases susceptibility to L. mexicana or L. amazonensis infection by inhibiting effector cell functions required for parasite killing. Here, IL10 is linked to infection.