Characterizing the anti-tumor response of T cell receptor gene-modified invariant natural killer T cells

Abstract

Abstract Human invariant NKT cells represent a distinct lymphocyte population that co-express an invariant antigen receptor and NK surface markers. Classic NKT cells express a restricted T cell receptor that recognizes lipids, such as α-Galactosylceramide (α-GalCer), in the context of CD1d. Activated iNKT cells produce a high level of cytokines, such as IFN- γ, thereby bridging innate and acquired immunity through the activation of other effector cells including dendritic cells (DCs), CD8 T cells, and NK cells. One major hurdle to studying the anti-tumor activity of iNKT cells is that they do not recognize antigens presented by classical MHC molecules and they have unknown tumor antigen specificity. Therefore, we expressed the MHC class I-restricted TIL 1383I TCR in human NKT cells to characterize their biology and tumor antigen-specific response. The 1383I TCR is a CD8 independent, high affinity TCR that recognizes the melanoma antigen, tyrosinase, presented by HLA-A2. Here, we report the expression and function of TIL 1383I TCR transduced human iNKT cells. iNKT cells stimulated with α-GalCer- pulsed DCs are transduced with the retroviral vector encoding the TIL1383I TCR. After confirming TIL 1383I TCR expression in iNKT cells by flow cytometry, we assess their anti-tumor activity and polyfunctionality by intracellular cytokine staining. TIL 1383I TCR transduced iNKT cells produced IFN-γ in response to tyrosinase loaded T2 cells and HLA-A2+/tyrosinase+ melanoma. These findings indicate that genetically engineered iNKT cells are useful to study their biology in the context of antigen specificity, as well as to generate new effector populations for the treatment of cancer patients.