Fig. 4.

Tumor antigen-specific T cell responses in skin-test infiltrating-lymphocyte cultures. a Induration of delayed-type hypersensitivity (DTH) sites measured 48 h after intradermal injection of VAC-DC or cytokine-matured DC (cDC) loaded with gp100 mRNA or tyrosinase mRNA. Data are shown in mm induration. Each dot represents one DTH site. The line indicates the mean of DTH sites. *** p < 0.001, ns not significant, paired t test. b Example of tetramer staining of T cells cultured from a DTH site of patient B-9. Cells were stained with allophycocyanin-labeled tetramers encompassing the gp100:154 peptide, gp100:280 peptide, tyrosinase peptide, or control peptide and with CD8-FITC. Numbers indicate the percentage of tetramer-positive cells CD8⁺ T cells of total CD8⁺ T cells. c IFNγ production by the same T cells of patient B-9 after stimulation with T2 cells loaded with tumor peptides or BLM cells expressing tumor proteins. d Kaplan–Meier analyses of overall survival according to the presence of tetramer-positive populations in skin-test infiltrating-lymphocyte cultures from DTH skin-test biopsies or in peripheral blood in HLA-A*02:01-positive stage IV patients. The presence of tumor antigen-specific T cells (Tc+) correlates with longer overall survival after VAC-DC vaccination in metastatic melanoma patients compared to patients without detectable tumor antigen-specific T cells (Tc-)