Vaccination with Antigen-Transfected, NKT Cell Ligand–Loaded, Human Cells Elicits Robust In Situ Immune Responses by Dendritic Cells

Abstract

Both innate and adaptive immunity are crucial for cancer immunosurveillance, but precise therapeutic equations to restore immunosurveillance in patients with cancer patients have yet to be developed. In murine models, a-galactosylceramide (a-GalCer)-loaded, tumor antigen-expressing syngeneic or allogeneic cells can act as cellular adjuvants, linking the innate and adaptive immune systems. In the current study, we established human artificial adjuvant vector cells (aAVC) consisting of human HEK293 embryonic kidney cells stably transfected with the natural killer T (NKT) immune cell receptor CD1d, loaded with the CD1d ligand a-GalCer and then transfected with antigen-encoding mRNA. When administered to mice or dogs, these aAVC-activated invariant NKT (iNKT) cells elicited antigen-specific T-cell responses with no adverse events. In parallel experiments, using NOD/SCID/IL-2rgc null -immunodeficient (hDC-NOG) mouse model, we also showed that the human melanoma antigen, MART-1, expressed by mRNA transfected aAVCs can be cross-presented to antigenspecific T cells by human dendritic cells. Antigen-specific T-cell responses elicited and expanded by aAVCs were verified as functional in tumor immunity. Our results support the clinical development of aAVCs to harness innate and adaptive immunity for effective cancer immunotherapy. Cancer Res; 73(1); 62-73. Ó2012 AACR.

Invariant NKT Cells Induce Plasmacytoid Dendritic Cell (DC) Cross-Talk with Conventional DCs for Efficient Memory CD8+ T Cell Induction

“…For in vitro transcription, these plasmids were linearized by restriction enzyme digestion, purified by a QIAquick PCR Purification Kit (QIAGEN), and used as a template. The RNAs were generated under a T7 promoter sequence on the vectors using an mMESSAGE mMACHINE T7 Ultra Kit (Ambion), as previously described (22). To load NIH3T3 cells with a-GalCer, the cells were cultured for 48 h in the presence of 500 ng/ml a-GalCer and then washed three times before transfection.…”

“…To maximally harness such immunological cascades, we established an efficient system using cells bearing a cell-associated Ag along with the iNKT cell ligand, a-galactosylceramide (a-GalCer). For example, we used iNKT ligand-loaded, tumor-associated Ag (TAA)-expressing CD1d + tumor cells (tumor/Gal) (19)(20)(21) or allogeneic fibroblasts loaded with a-GalCer transfected with TAA mRNA (16,22).…”

Systemic DC Activation Modulates the Tumor Microenvironment and Shapes the Long-Lived Tumor-Specific Memory Mediated by CD8+ T Cells

“…On the basis of these evidences, we previously illustrated the concept of a unique approach of using NKT ligand-loaded CD1d þ allogeneic cells transfected with tumor antigen mRNA as artificial adjuvant vector cells (aAVC; refs. 16,17). The first generation of aAVCs demonstrated certain of its immunologic features inducing both innate and adaptive immunity in the lymphoid organs through antigen-captured DCs in situ.…”

Characterization of the myeloid-derived suppressor cell subset regulated by NK cells in malignant lymphoma

“…[19][20][21] We and other researchers previously demonstrated that dendritic cell (DC) therapy increases the activation of NK cells against tumor cells [22][23][24] and that CD1d C cells loaded with invariant NKT cell ligand generate NKT cell-mediated protection against tumor cells. 25 Although there are reports in tumor-bearing mice of interactions between NK cells and various types of myeloid cells, i.e., DCs, macrophages, MDSCs, it is unclear whether NK cells influence the number or function of MDSCs.…”