Acid-Triggered Degradable Reagents for Differentiation of Adaptive and Innate Immune Responses to Leishmania-Associated Sugars.

Lipopolysaccharides (LPS) of Leishmania spp are known to alter innate immune responses. However, the ability of these sugars to specifically alter adaptive T-cell responses is unclear. To study cap sugar-T-cell interactions, pathogen mimics (namely glycodendrimer-coated latex beads with acid-labile linkers) were synthesized. Upon lysosomal acidification, linker breakdown releases glycodendrimers for possible loading on antigen presenting molecules to induce T-cell growth. T-cell proliferation was indeed higher after macrophage exposure to mannobioside or -trioside-containing glycodendrimers than to non-functionalized beads. Yet, blocking phagolysosomal acidification only reduced T-cell proliferation with macrophages exposed to beads with an acid-labile-linker and not to covalently-linked beads. These sugar-modified reagents show that oligosaccharides alone can drive T-cell proliferation by acidification-requiring presentation, most significantly in NKT receptor (CD160)-restricted T cells.