Both interleukin-4 (IL-4) and IL-4 receptor alpha signaling contribute to the development of hepatic granulomas with optimal antileishmanial activity.

The roles of interleukin-4 (IL-4) and IL-13 in the regulation of immunity to Leishmania donovani infection are still poorly understood. Here we show that the increased parasite load observed in IL-4(-/-) and IL-4 receptor alpha(-/-) mice correlates with retarded granuloma maturation and antileishmanial activity and that the increased parasite load observed in IL-4 receptor alpha(-/-) mice correlates with increased NOS2 expression and decreased serum gamma interferon levels. IL-4 and IL-13 appear to play little role in regulating collagen deposition in L. donovani-induced granulomas.