IFNG and leishmaniasis: IL-6 is one of the greatest oxymora in leishmaniasis because multiple studies have reported discordant results and it has been suggested to promote, suppress or effect no change in host defense to Leishmania. For instance, deletion of endogenous IL-6 in C57BL/6 mice enhanced control of L. donovani replication together with increased levels of circulating IFN-γ [61].