Cytokine profile and nitric oxide levels in macrophages exposed to Leishmania infantum FML.

Fucose-mannose ligand (FML) is a soluble antigen purified from Leishmania donovani complex and used for diagnosis, prognosis, and vaccine development against visceral leishmaniasis (VL). We aimed to explore the effects of FML on the production of cytokines, chemokines and nitric oxide (NO) by macrophages in vitro. Peritoneal macrophages from BALB/c mice were treated with various concentrations of FML purified from Leishmania infantum in the absence or presence of LPS Peritoneal macrophages. After 48hr, cell culture supernatants were recovered and the levels of TNF-α, IL-10, IL-12p70 and IP-10 measured by Sandwich ELISA and NO concentration by Griess reaction. We found that FML significantly increase NO, IL-12p70 and IP-10 production in both LPS-treated and untreated macrophages and increase IL-10 levels only in LPS-treated macrophages. However, FML could not alert TNF-α levels in both LPS-treated and untreated macrophages. Further analysis revealed that FML can also increase IL-12p70/IL-10 ratio in LPS-treated macrophages. We concluded that FML can polarize macrophages to an appropriate phenotype similar to M1 phenotype against Leishmania donovani complex, although IL10 and TNF results are controversial.