Interaction of Leishmania parasites with dendritic cells and its functional consequences.

Interaction between dendritic cells (DC) and T cells is essential for the generation of cell mediated immunity and thus DC play a critical role in the initiation of immune responses against Leishmania parasites. Although macrophages (Mphi) are the major targets of all species of Leishmania, a number of studies demonstrated the infection of DC by Leishmania. DC specific intracellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN), has been reported to be the receptor for Leishmania amastigotes. The functional consequences in DC after Leishmania infections appear to depend on species of Leishmania. Some species of Leishmania enhance the surface expression of co-stimulatory molecules and CD40-ligand-induced IL-12 production in DC. On the other hand other species down-regulate co-stimulatory molecules and inhibit IL-12 production. The intrinsic differences among Leishmania species with regard to alteration of cell surface molecules and IL-12 production in DC may contribute to the healing and non-healing forms of the disease.