Classically, IL-12 production by antigen presenting cells leads to IFN-γ production by T cells.34 However, as seen with LJM19, strong induction of IL-4 can suppress IFN-γ despite high levels of IL-12.35 This co-expression of IL-12 and IL-4 mirrors the cytokine profile seen in LJM19-immunized hamsters protected against L. donovani challenge,26 suggesting that protection from leishmaniasis is not solely dependent on IFN-γ production but rather on the balance of TH cytokines. This evidence concerns the gene IFNG and leishmaniasis.