For this reason, we employed the well-characterized BALB/c model of CL by L. amazonensis [18,26] in which animals are susceptible to infection and develop chronic lesions [40,47] in the presence of IL-4 and IL-10, in contrast with C57BL/6 mice, where these two Th2-characteristic cytokines seem to have no relevance [24]. The gene discussed is IL4; the disease is infection.