AUTHOR=Li Rui-Jun Eveline , Hogervorst Tim P. , Achilli Silvia , Bruijns Sven C. M. , Spiekstra Sander , Vivès Corinne , Thépaut Michel , Filippov Dmitri V. , van der Marel Gijs A. , van Vliet Sandra J. , Fieschi Franck , Codée Jeroen D. C. , van Kooyk Yvette TITLE=Targeting of the C-Type Lectin Receptor Langerin Using Bifunctional Mannosylated Antigens JOURNAL=Frontiers in Cell and Developmental Biology VOLUME=8 YEAR=2020 URL=https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2020.00556 DOI=10.3389/fcell.2020.00556 ISSN=2296-634X ABSTRACT=

Langerhans cells (LCs) are antigen-presenting cells that reside in the skin. They uniquely express high levels of the C-type lectin receptor Langerin (CD207), which is an attractive target for antigen delivery in immunotherapeutic vaccination strategies against cancer. We here assess a library of 20 synthetic, well-defined mannoside clusters, built up from one, two, and three of six monomannosides, dimannosides, or trimannosides, appended to an oligopeptide backbone, for binding with Langerin using surface plasmon resonance and flow cytometric quantification. It is found that Langerin binding affinity increases with increasing number of mannosides. Hexavalent presentation of the mannosides resulted in binding affinities ranging from 3 to 12 μM. Trivalent presentation of the dimannosides and trimannosides led to Langerin affinity in the same range. The model melanoma gp100 antigenic peptide was subsequently equipped with a hexavalent cluster of the dimannosides and trimannosides as targeting moieties. Surprisingly, although the bifunctional conjugates were taken up in LCs in a Langerin-dependent manner, limited antigen presentation to cytotoxic T cells was observed. These results indicate that targeting glycan moieties on immunotherapeutic vaccines should not only be validated for target binding, but also on the continued effects on biology, such as antigen presentation to both CD8+ and CD4+ T cells.