Meglumine antimonate treatment enhances phagocytosis and TNF-α production by monocytes in human cutaneous leishmaniasis

This work evaluated phagocytic function, hydrogen peroxide (H2O2), TNF-α and IL-10 production by monocytes and serum INF-γ levels in New World human cutaneous leishmaniasis and the influence of meglumine antimonate treatment on these immune functions. The phagocytic capacity of monocytes in untreated Leishmania-infected individuals was significantly (2.5 times) lower than that of healthy controls, and antimonial treatment increased the phagocytosis by monocytes by about five times at the end of therapy. The leishmaniasis patients showed 3.9 times higher H2O2 production than controls and treatment with meglumine antimonate did not influence the production of H2O2, which remained enhanced until the end of treatment. Individuals with leishmaniasis showed 6.3 times lower TNF-α production than healthy individuals and meglumine antimonate treatment caused a significant increment (11.9 times) in its production. INF-γ serum levels were higher in Leishmania-infected individuals than healthy controls, and the production of IL-10 by monocytes was not influenced by infection or antimonial treatment. Enhancement of monocyte functions by the antimonial treatment suggests that the immunomodulatory effects of the drug may also play a part in the way meglumine antimonate acts against the parasite in human leishmaniasis, by directly increasing phagocytosis and TNF-α production.