The role of mannose receptor during experimental leishmaniasis.

The primary host cells for Leishmania replication are macrophages (MP). Several molecules on the surface of professional phagocytic cells have been implicated in the initial process of parasite internalization and initiation of signaling pathways. These pattern recognition receptors distinguish molecular patterns on pathogen surfaces. Mannose receptor (MR), specifically, recognizes mannose residues on the surface of Leishmania parasites. We studied the role of MR in the pathogenesis of experimental cutaneous and visceral leishmaniasis using MR-deficient [MR-knockout (KO)] C57BL/6 mice. MR-deficient MP exhibited a comparable infection rate and cytokine production. In the absence of MR, the clinical course of Leishmania major and Leishmania donovani infections was similar in MR-KO and wild-type mice (MR-WT). Furthermore, immunohistochemistry of cutaneous lesions from MR-KO and MR-WT mice revealed no differences in lesion architecture or cell components. Inhibition of MP responses is a hallmark of Leishmania infection; our data demonstrate further that host MR is not essential for blocking IFN-gamma/LPS-induced IL-12 production and MAPK activation by Leishmania. Thus, we conclude that the MR is not essential for host defense against Leishmania infection or regulation of IL-12 production.