NKT cell-driven enhancement of antitumor immunity induced by Clec9a-targeted tailorable nanoemulsion.

Invariant natural killer T (iNKT) cells are a subset of lymphocytes with immune regulatory activity. Their ability to bridge the innate and adaptive immune systems has been studied using the glycolipid ligand a-galactosylceramide (alpha GC). To better harness the immune adjuvant properties of iNKT cells to enhance priming of antigen-specificCD8(+) T cells, we encapsulated both alpha GC and antigen in a Clec9a-targeted nanoemulsion (TNE) to deliver these molecules to cross-presenting CD8(+) thorn dendritic cells (DC). We demonstrate that, even in the absence of exogenous glycolipid, iNKT cells supported the maturation of CD8 alpha(+) DCs to drive efficient cross-priming of antigen-specific CD8(+) T cells upon delivery of Clec9a/OVA-TNE. The addition of alpha GC to the TNE (Clec9a/OVA alpha GC) further enhanced activation of iNKT cells, NK cells, CD8 alpha(+) thorn DCs, and polyfunctional CD8(+) T cells. When tested therapeutically against HPVE7-expressing TC-1 tumors, long-term tumor suppression was achieved with a single administration of Clec9a/E7 peptide/alpha GC TNE. Antitumor activity was correlated with the recruitment of mature DCs, NK cells, and tumor-specific effector CD8(+) T cells to the tumor-draining lymph node and tumor tissue. Thus, Clec9a-TNE codelivery of CD8(+) T-cell epitopes with alpha GC induces alternative helper signals from activated iNKT cells, elicits innate (iNKT, NK) immunity, and enhances antitumor CD8(+) T-cell responses for control of solid tumors.