Dendritic Cell (DC)-specific Intercellular Adhesion Molecule 3 (ICAM-3)-grabbing Nonintegrin (DC-SIGN, CD209), a C-type Surface Lectin in Human DCs, Is a Receptor for LeishmaniaAmastigotes

Marı́A Colmenares,Amaya Puig-Kröger,Oscar Muñiz Pello,Angel L Corbı́,Luis Rivas

doi:10.1074/jbc.m205270200

Abstract

Dendritic cells (DCs) play a critical role in the initiation of the immunological response against Leishmania parasites. However, the receptors involved in amastigote-dendritic cell interaction are unknown, especially in absence of opsonizing antibodies. We have studied the interaction of Leishmania pifanoi axenic amastigotes with the C-type lectin DC-specific intercellular adhesion molecule (ICAM)-3-grabbing nonintegrin (DC-SIGN, CD209), a receptor for ICAM-2, ICAM-3, human immunodeficiency virus gp120, and Ebola virus. L. pifanoi amastigotes interact with immature human dendritic cells and CD209-transfected K562 cells in a time- and dose-dependent manner. Leishmania amastigote binding to human dendritic cells and DC-SIGN-transfected cells is inhibited by a function-blocking DC-SIGN-specific monoclonal antibody. More importantly, this monoclonal antibody dramatically reduces internalization of Leishmania amastigotes by immature human DCs. These results constitute the first description of a nonviral pathogen ligand for DC-SIGN and provide evidence for a relevant role of DC-SIGN in Leishmania amastigote uptake by dendritic cells. Our finding has important implications for Leishmania host-cell interaction and the immunoregulation of cutaneous leishmaniasis.

Highlights

Leishmaniasis is a vector-borne parasitic disease with a broad range of clinical manifestations, from local cutaneous lesions to life-threatening visceral disease, mainly caused by differences among Leishmania species and the immunological status of the mammalian host
We have studied the interaction of Leishmania pifanoi axenic amastigotes with the C-type lectin Dendritic cells (DCs)-specific intercellular adhesion molecule (ICAM)-3-grabbing nonintegrin (DC-SIGN, CD209), a receptor for ICAM-2, ICAM-3, human immunodeficiency virus gp120, and Ebola virus
In order to explore whether DC-SIGN was involved in amastigote binding, we first analyzed the interaction of axenic amastigotes with K562 cells transfected with DC-SIGN (K562CD209 cells)

Summary

EXPERIMENTAL PROCEDURES

Reagents and Antibodies—The DC-SIGN-specific monoclonal antibody (MR-1) has been described previously [18]. Cells were washed with PBS-1 mM EDTA and preincubated for 10 min at room temperature with either MR-1 antibody (1.2 ␮g/ml, unless otherwise indicated), irrelevant antibodies (100 ␮g/ml human immunoglobulins or 16 ␮g/ml anti-CD18 TS1/18 isotype control), EGTA (5 mM), soluble mannan (300 ␮g/ml), or purified L. pifanoi amastigote glycosylinositolphospholipids (5 ␮g/ml) in complete medium before parasite addition. MDDCs were labeled in complete medium with the fluorescent dye 2Ј,7Ј-bis-(2-carboxyethyl)-5(and-6)-carboxyfluorescein acetoxymethyl ester (Molecular Probes) and preincubated for 20 min at 37 °C in RPMI 1640 medium containing 0.4% bovine serum albumin and function-blocking antibodies against CD209 (MR-1), CD18 (TS1/18), or mannan at 100 ␮g/ml. Cells were washed with PBS-1 mM EDTA and preincubated for 10 min at room temperature with either MR-1, TS1/18, or soluble mannan in complete medium before parasite addition. The percentage of infected DCs and the parasite:DC ratio were determined by light microscopy examination of at least 200 cells

RESULTS

DC:parasite ratio

DISCUSSION