Functional and antigenic characterization of human, rhesus macaque, pigtailed macaque, and murine DC-SIGN

DC-SIGN, a type II membrane protein with a C-type lectin binding domain tha t is highly expressed on mucosal dendritic cells (DCs) and certain macropha ges in vivo, binds to ICAM-3, ICAM-2, and human and simian immunodeficiency viruses (HIV and SIV). Virus captured by DC-SIGN can be presented to T cel ls, resulting in efficient virus infection, perhaps representing a mechanis m by which virus can be ferried via normal DC trafficking from mucosal tiss ues to lymphoid organs in vivo. To develop reagents needed to characterize the expression and in vivo functions of DC-SIGN, we cloned, expressed, and analyzed rhesus macaque, pigtailed macaque, and murine DC-SIGN and made a p anel of monoclonal antibodies (MAbs) to human DC-SIGN. Rhesus and pigtailed macaque DC-SIGN proteins were highly similar to human DC-SIGN and bound an d transmitted HIV type 1 (HIV-1), HIV-2, and SIV to receptor-positive cells . In contrast, while competent to bind virus, murine DC-SIGN did not transm it virus to receptor-positive cells under the conditions tested. Thus, mere binding of virus to a C-type lectin does not necessarily mean that transmi ssion will occur. The murine and macaque DC-SIGN molecules all bound ICAM-3 . We mapped the determinants recognized by a panel of 16 MAbs to the repeat region, the lectin binding domain, and the extreme C terminus of DC-SIGN. One MAb was specific for DC-SIGN, failing to cross-react with DC-SIGNR. Mos t MAbs crossreacted with rhesus and pigtailed macaque DC-SIGN, although non e recognized murine DC-SIGN. Fifteen of the MAbs recognized DC-SIGN on DCs, with MAbs to the repeat region generally reacting most strongly. We conclu de that rhesus and pigtailed macaque DC-SIGN proteins are structurally and functionally similar to human DC-SIGN and that the reagents that we have de veloped will make it possible to study the expression and function of this molecule in vivo.