Autocrine, Not Paracrine, Interferon-Gamma Gene Delivery Enhances Ex Vivo Antigen-Specific Cytotoxic T Lymphocyte Stimulation and Killing

Abstract EN

The adoptive transfer of antigen-specific cytotoxic T lymphocytes (CTL) shows promise in the treatment of cancer and infectious diseases.

We utilize adeno-associated virus-(AAV-) based antigen gene-loaded dendritic cells (DCs) to stimulate such antigen-specific CTL.

Yet further improvements in CTL stimulation and killing may result by gene delivery of various Th1-response interferons/cytokines, such as interferon γ (IFN-γ), as the delivered gene can continuously produce that interferon.

However which immune cell type should optimally express IFN-γ is unclear as the phenotypes of both DC and T cells are enhanced by it.

Here, we used AAV to compare and contrast IFN-γ gene delivery into DC or T cells, and versus the addition of exogenous IFN-γ, for stimulating carcinoembryonic antigen-(CEA-) specific CTL.

It was found that AAV/IFN-γ delivery into T cells (autocrine) resulted in T cell populations with the highest CD8(+)/CD4(+) ratio, highest IFN-γ(+)/IL-4(+) ratio, highest CD69(+),CD8(+) levels, and lowest CD4(+)/CD25(+) levels, all consistent with the strongest Th1 response.

Most importantly, AAV/IFN-γ transduction of T cells resulted in antigen-specific T cell populations with the highest killing capabilities, 49% above other treatments.

These data strongly suggest that AAV/IFN-γ autocrine gene delivery into T cells is worthy of further study towards maximizing the generation of antigen-specific anticancer CTL killers.