Nitric oxide and cellular immunity in experimental cutaneous leishmaniasis.

We examined the local and systemic production of nitric oxide (NO) and the pattern of cytokine during the course of Leishmania mexicana infection in susceptible BALB/c and resistant C57BL/6 mice. NO derivatives were measured in serum, and the expression of inducible nitric oxide synthase (iNOS), interferon (IFN-gamma), interleukin (IL-4) and epidermal Langerhans cells (LC) was measured in the lesions by immunohistology. Circulating NO concentrations, iNOS+ cell density, IFN-gamma+ Th1 cells and CD205+ Langerhans cells were higher in early lesions of resistant C57BL/6 mice. In contrast, susceptible BALB/c mice developed chronic and progressive lesions with a predominance of IL-4+ Th2 cells. In both susceptible and resistant mice, lesion size and lymph node volume followed a similar course. The early local and systemic production of NO in resistant mice may be related with the premature production of IFN-gamma observed, contributing to the resolution of the lesion.