Leishmania amazonensis is one of the agents in a wide spectrum of clinical forms of
cutaneous leishmaniasis. In general, the resistance against leishmaniasis depends on the
development of an efficient immune response, however many studies have demonstrated that
specific cytokines or combinations of cytokines may be factors of resistance or susceptibility
to infection by L. amazonensis. Recent studies suggest the involvement of Langerhans cells
(LCs) in the anti-Leishmania response, but the mechanisms involved in this interaction are
still poorly understood. In this study, we investigated the role of TNF-α and anti-CD40 in L.
amazonensis interaction with LCs in vitro, showing de profile of cytokines produced and the
expression of surface molecules, besides verifing their abilities to activate the production of
IFN-γ e IL-4 by lymph node cells. Methods: Fresh immature LCs, highly purified from
BALB/c mouse skin, were incubated with L. amazonensis promastigotes, TNF-α and/or anti-
CD40 mAb. After 24 h, LCs were co-cultured with lymph nodes cells of BALB/c mice for
additional 72h. Culture supernatants were tested for IL-6, IL-12p70, IFN-γ and IL-4 by
ELISA, while surface molecules were analyzed by FACS. Results: The levels of IL-6 and IL-
12p70 produced by LCs were significantly reduced after interaction with L. amazonensis,
even after treatment of LCs with TNF-α or anti-CD40. Regarding surface molecules, there
was no difference in the expression of CD207 in both groups, but the presence of L.
amazonensis promoted a significant reduction in the expression of CD40 on LCs treated with
TNF-α or anti-CD40, and increased expression CD86 in all groups. Lymph node cells showed
a decreased production of IFN-γ in the presence of L. amazonensis and no change in IL-4.
When co-cultured with LCs previously stimulated with L. amazonensis, the production of
IFN-γ was also reduced, even in the presence of TNF-α and/or anti-CD40. No significant
changes were observed in IL-4 by lymph cells co-cultured under the same experimental
conditions. Conclusion: L. (L.) amazonensis exert an immunomodulatory effect on the
immune response mediated by LCs by: 1) inhibiting the production of IL-6 and IL-12p70; 2)
decreasing CD40 expression and; 3) preventing the activation of IFN-γ production by lymph
node cells co-cultured with LCs, even after treatment with TNF-α and anti-CD40 antibody.
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