Fig. 4.

Co-release of IL-2 and anti-CTLA-4 from aAPCs enhanced the expansion and cytotoxicity of melanoma antigen-specific CD8⁺ T cells ex vivo. Naïve splenocytes from C57BL/6J mice were co-incubated for 7 days with blank PLGA-MPs and each type of aAPC. a, b The frequencies of TRP2_180–188-specific CD8⁺ T cells (top row) and OVA_257–264-specific CD8⁺ T cells (bottom row) in the co-culture group of blank PLGA-MPs, aAPC, aAPC^IL-2, aAPC^anti-CTLA4, aAPC^{IL-2+anti-CTLA4}, aAPC exogenous IL-2/anti-CTLA-4, or aAPC^IL-2 + aAPC^anti-CTLA4, as detected by H-2K^b/TRP2_180–188 dimer or H-2K^b/OVA_257–264 dimer staining. Numbers in the top left of the flow cytometric dot plots represent the percentage of TRP2_180–188 dimer- or OVA_257–264 dimer-positive cells in the CD8⁺ T cell population. c, d Cytotoxicity of the splenocytes from the five co-culture groups of a and the three co-culture groups of b. The resulting splenocytes were further co-cultured with target cells for 4 h at various E:T ratios followed by 7-AAD staining to analyze the antigen-specific cytolysis of B16, SP2/0, and S180 tumor cells. e, f Representative flow cytometric histograms of 7-AAD staining for B16 cells for the five co-culture groups of c and the three co-culture groups of d. These data were from one representative experiment of three independent experiments