Increased interleukin 4 (IL-4) receptor expression and IL-4-induced decrease in IL-12 production by Langerhans cells infected with Leishmania major.

Langerhans cells (LC) take up Leishmania major and are critical for the induction of the parasite-specific T-cell response. Their functional activities are regulated by cytokines. We analyzed whether infection of LC with L. major modulates the expression of their cytokine receptors. The expression of the interleukin 4 (IL-4) receptor was increased on infected LC from susceptible mice but not on those from resistant mice. Moreover, IL-4 treatment strongly decreased the lipopolysaccharide-induced IL-12 response of infected LC from susceptible mice. This modulation of IL-4 receptor expression and IL-12 production by infection of LC with Leishmania may contribute to the development of Th2 cells and to susceptibility to infection.