DC capture antigen and process it internally to form MHC-peptide complexes. Following antigen uptake, DC may migrate from the periphery to lymph nodes, where they can present MHC-peptide complexes to resting T cells. This initial contact between DC and resting T cells is proposed to occur via a dendritic cell-specific, ICAM-3 grabbing non-integrin (DC-SIGN)-ICAM-3 interaction.
DC-SIGN was originally discovered as a C-type lectin capable of binding the HIV-1 envelope glycoprotein gp1201. The restricted expression of DC-SIGN on DC highlights two of DC contrasting functions: initiation of immuno-stimulatory responses and promotion of the binding and transmission of HIV-1 to T cells.