Fig. 6.

Anti-CD137 produced by implanted microcapsules enhances antitumor CTL activity. Groups of mice bearing CT26 tumors were treated as in Fig. 4, and on day 14 subjected to assays measuring the CTL response against the H-2L^d restricted epitope AH1. a IFNγ ELISPOTs of spleen lymphocytes stimulated with AH1 synthetic peptides were quantitated comparing tumor-naïve mice, non-treated animals and animals treated with anti-CD137 mAb 2A intraperitoneally or mice implanted with the 2A-producing microcapsules. Data represent mean ± SD of spot-forming cells in a total of 10⁶ spleen lymphocytes. A representative experiment with six animals per group is shown. b In vivo cytotoxicity was tested in mice treated in parallel and the specific cytotoxic activity against autologous splenocytes pulsed with the AH1 synthetic peptide was assessed. Data represent the mean ± SD of a representative experiment with six animals per group. c Mice cured of tumor (n = 9), as those shown in Fig. 4, were challenged with CT26 cells once they were tumor free for 4–5 weeks. Sequential follow-up of the tumor size is presented. As a control, tumor-naïve mice (n = 4) were used