Antitumor Activity of Ex Vivo Expanded Tumor Antigen Priming Cytotoxic T Cells Against Malignant Melanoma

Abstract

Background/aim: Dendritic cells (DCs) can capture antigens from tissues and migrate to lymph nodes, where they cross-present cell-associated antigens to cluster of differentiation (CD) 8⁺ T cells by major histocompatibility complex (MHC) I. Cytotoxic T lymphocytes remove malignant cells through T-cell receptor recognition of specific peptides that appear on the surface of cancer cells by the MHC I/beta-2-microglobulin complex. This study aimed to investigate the antitumor activity of ex vivo expanded, tumor antigen-primed cytotoxic T cells against malignant melanoma.

Materials and methods: T cells were induced using DC-T cell coculture and peripheral blood mononuclear cell (PBMC) methods, with and without Melan-A/MART-1 peptide stimulation. Melan-A streptamers were used for T-cell analysis. Interferon-γ and granzyme B secretion levels were measured at 1 and 2 weeks. T-cell subtypes were analyzed, and cytotoxic activity against melanoma cells was evaluated.

Results: The number of positive spots significantly increased over time. CD4⁺ and CD8⁺ T cells expanded, and CD4⁺ T cells were the dominant T-cell subtype. The number of tumor cells (SK-MEL-28) decreased according to the cytotoxic T lymphocyte:T ratio. Cytotoxicity was observed immediately after coculture and gradually increased over 72 h.

Conclusion: DCs pulsed with killed allogeneic melanoma cells effectively cross-prime cytotoxic T cells that specifically target the Melan-A antigen. Moreover, naive CD8⁺ T cells primed by Melan-A-loaded DCs successfully killed malignant melanoma cells, highlighting a promising strategy for adoptive immunotherapy against melanoma.

Keywords: CD4+/CD8+ T cell; Dendritic cell; Melan-A antigen; malignant melanoma.