Glycan-binding profile of DC-like cells

Modification of vaccine carriers by decoration with glycans can enhance binding to and even targeting of dendritic cells (DCs), thus augmenting vaccine efficacy. To find a specific glycan-"vector" it is necessary to know glycan-binding profile of DCs. This task is not trivial; the small number of circulating blood DCs available for isolation hinders screening and therefore advancement of the profiling. It would be more convenient to employ long-term cell cultures or even primary DCs from murine blood. We therefore examined whether THP-1 (human monocyte cell line) and DC2.4 (immature murine DC-like cell line) could serve as a model for human DCs. These cells were probed with a set of glycans previously identified as binding to circulating human CD14^low/-CD16⁺CD83⁺ DCs. In addition, we tested a subpopulation of murine CD14^low/-CD80⁺СD11c⁺CD16⁺ cells reported as relating to the human CD14^low/-CD16⁺CD83⁺ cells. Manα1-3(Manα1-6)Manβ1-4GlcNAcβ1-4GlcNAcβ bound to both the cell lines and the murine CD14^low/-CD80⁺СD11c⁺CD16⁺ cells. Primary cells, but not the cell cultures, were capable of binding GalNAcα1-3Galβ (A_di), the most potent ligand for binding to human circulating DCs. In conclusion, not one of the studied cell lines proved an adequate model for DCs processes involving lectin binding. Although the glycan-binding profile of BYRB-Rb (8.17)1Iem mouse DCs could prove useful for assessing human DCs, important glycan interactions were missing, a situation which was aggravated when employing cells from the BALB/c strain. Accordingly, one must treat results from murine work with caution when seeking vaccine targeting of human DCs, and certainly should avoid cell lines such as THP-1 and DC2.4 cells.