Tu151 - Development of Novel Agonists for Human Inkt Cells

Abstract Text: Invariant natural killer T (iNKT) cells are CD1d-restricted T cells expressing a semi-invariant T cell receptor (TCR) that recognizes lipid antigens and is involved in the anti-cancer immune response. Studies of a prototypic iNKT cell antigen, α-galactosylceramide (α-GalCer), analogs have shown that ceramide structure affects the activities of mouse iNKT cells. However, much less has been studied on human iNKT cells. This study evaluated the antigenicity of eight novel sulfatide-based lipids synthesized with fluorobenzene at the acyl chain terminus and three sphingoid base structures. Using human CD1d-tetramers loaded with sulfatide analogs, we examined the recognition of the sulfatide analogs by the TCR of human iNKT cells in peripheral blood mononuclear cells (PBMCs) from three donors. One analog we named SAP-3 was commonly recognized by all donors' iNKT cells. Sulfatide analogs activated iNKT cells measured by CD69 and CD25 induction in a CD1d-dependent manner. Cytokine analyses revealed donor-specific variability, with the commonly recognized analog SAP-3 inducing IL-2 production, unlike α-GalCer. To test the hypothesis that this analog SAP-3 enhances T cell activation and proliferation, we stimulated PBMC-derived CD8 T cells with influenza matrix protein-derived peptides and this analog SAP-3. The results showed that administration of this analog SAP-3 did not change the frequency of influenza-specific CD8 T cells. However, it increased the proportion of poly-functional CD8 T cells producing the three cytokines (IFN-γ, IL-2, and TNF-α) and two cytokines (IFN-γ and IL-2). These data suggested that the sulfatide analog SAP-3 could be used as a vaccine adjuvant inducing polyfunctional T cells.