Figure 5

HGF limits CTL responses by modulating APC functions. Highly purified CD11c⁺ DCs were cultured for 24 h with either HGF or vehicle and then co-cultured with purified Pmel-1 CD8⁺ T cells in the presence of IL-2 and gp100_25-33 for 5 days. (a) HGF-treated DCs induced low levels of CD8⁺ T-cell proliferation, as measured at day 5 by [³H] thymidine incorporation. Values are expressed as counts per minute (cpm). Data are representative of three independent experiments with similar results. *P <0.05; **P <0.01 by Student’s t-test. (b) CD8⁺ T cells co-cultured with HGF-treated DCs demonstrated dramatically reduced specific cytotoxicity compared with T cells co-cultured with control PBS-treated DCs (right panel). gp100_25-33-stimulated CD8⁺ T cells did not lyse non-pulsed EL-4 target cells (left panel). Results are the mean ± SEM of three independent experiments carried out in triplicates.