IFNG and visceral leishmaniasis: Moreover, in human leishmaniasis, the different clinical outcomes do not appear to be associated with polarized Th1- or Th2-type responses: whereas IL-4 is higher in the plasma of patients with visceral leishmaniasis (VL) (28,29), a number of proinflammatory cytokines such as IL-1, IL-6, IL-12, IFN-γ and TNF-α are also increased (30,31).