IL6 and leishmaniasis: The results obtained shed new light on the apparent dual role of eosinophils in leishmaniasis: they can inflict crucial damage to the parasite showing a healing effect, whereas they can also cause worsening of the disease by producing cytokines such as IL-6, IL-8 and IL-13 upon contact with the parasite, associating eosinophils with disease severity and pathological conditions.