Immuno-biochemical variation in susceptible BALB/c and resistant C57BL/6 mice infected with Iranian strain of cutaneous leishmaniasis; Leishmania major MRHO/IR/75/ER

Background: Cutaneous infection caused by Leishmania is a major worldwide health problem, with high endemicity in developing countries. Methods: In the current study, we compared production of nitric oxide (NO) and reactive nitrogen intermediates (RNI) in two different hosts (susceptible BALB/c and resistant C57BL mice) infected with L. major. Exprimental leishmaniasis was initiated by subcutaneous (s.c.) injection of promastigotes into the basal tail test groups. The development of lesions was determined weekly by measuring the two diameters. After 10 weeks, all mice were killed humanly by terminal anesthesia and target tissues including lymph node, spleen and liver from each mouse were removed, weighted and their impression smears were also prepared. Results: Disease period, macroscopic features, lesion sizes, RNI levels in plasma and also in liver and spleen suspensions, proliferation of amastigotes inside macrophages, visceralization of parasite and hepatosplenomegaly in both susceptible and resistant mice infected with L. major was compared. Results from this investigation clear that differences between susceptible BALB/c and resistant C57BL mice were correlated with immuno-biochemical factors and clearly point to a partial involvement of NO in the cytotoxic activity of macrophages against this parasite. Conclusions: Analysis of data resulted from this study revealed an association between RNI levels with the evolution of disease, which had effects on pathological sign of L. major infected mice. The modulation of NO was able to modify these clinical signs and could affect the proliferation of amastigotes inside macrophages, lesion sizes, survival rates, degree of splenomegaly / hepatomegaly and presence of amastigotes in lesion smears of liver, spleen and lymph node.