Since the longstanding expression of inducible NO synthase is related to the persistence of Leishmania within host macrophages (Bogdan et al., 1996), it is plausible to suggest that another cell type involved in the infection course could allow the maintenance of this pathogen in certain organs where adipocytes are abundant, such as skin and viscera, which are relevant to specific clinical manifestations of different Leishmania species. This evidence concerns the gene NOS2 and infection.