Mutz-3-derived Langerhans cells are a model to study HIV-1 transmission and potential inhibitors.

Sexual transmission is the primary route of HIV-1 infection, and DC subsets are thought to be involved in viral dissemination to T cells. In the genital mucosa, two main subsets of DCs are present: epithelial LCs capture and degrade HIV-1 through C-type lectin Langerin, whereas subepithelial DCs express DC-SIGN, which facilitates HIV-1 transmission to T cells. As there is currently no HIV-1 vaccine available, microbicides provide an alternative strategy to limit HIV-1 spread. However, research into the function of LCs is hampered by the low availability and donor differences. Here, we set out to investigate whether LCs derived from the Mutz-3 cell line (Mu-LCs) provide a valuable tool to investigate the role of LCs in HIV-1 transmission and identify suitable potential microbicides. We demonstrate that Mu-LCs phenotypically resemble human primary LCs; Mu-LCs do not transmit HIV-1 efficiently, and inhibition of Langerin enhances HIV-1 transmission to T cells. We show that carbohydrate structures blocking DC-SIGN but not Langerin are potential microbicides, as they prevent HIV-1 transmission by DCs but do not affect the antiviral function of LCs. Therefore, Mu-LCs are a suitable model to investigate the role of LCs in HIV-1 transmission and to screen potential microbicides.