Arginase-2-specific cytotoxic T cells specifically recognize functional regulatory T cells

Area of Science:

• Immunology
• Cancer Biology
• Metabolic Enzyme Function

Background:

• High arginase-2 (ARG2) expression in the tumor microenvironment (TME) depletes arginine (L-Arg), impairing T cell function and suppressing anti-cancer immunity.
• Previous studies identified ARG2-specific CD4 T cells that inhibit tumor growth in murine models.
• This study investigates the presence and function of ARG2-specific CD8 T cells in healthy donors and cancer patients within the TME.

Purpose of the Study:

• To investigate the natural occurrence of ARG2-specific CD8 T cells in healthy donors and cancer patients.
• To assess the immunomodulatory capabilities of ARG2-specific CD8 T cells within the TME.
• To evaluate the potential of ARG2-based vaccines for cancer immunotherapy.

Main Methods:

• Screening of ARG2-derived peptides in human peripheral blood mononuclear cells using IFN-γ ELISPOT.
• Establishment and characterization of ARG2-specific CD8 T cell cultures.
• Assessment of T cell reactivity against ARG2-expressing cancer cells and regulatory T cells (Tregs).
• In vivo vaccination studies in a murine tumor model (Pan02) with subsequent analysis of tumor tissue.

Main Results:

• Existence of ARG2-specific CD8+ T cells demonstrated in both healthy donors and cancer patients.
• These T cells recognize ARG2-derived peptides presented by HLA-B8 and exhibit cytotoxic function against ARG2-expressing cancer cells.
• ARG2-specific T cells effectively recognize and react to activated Tregs with high ARG2 expression.
• Vaccination with ARG2-derived epitopes in a murine model led to tumor growth suppression and antitumorigenic immunomodulation.

Conclusions:

• ARG2-specific T cells can modulate the immunosuppressive TME.
• ARG2-based immunomodulatory vaccines represent a promising strategy for cancer immunotherapy.