Vaccination induces NK, CTL and cytokine responses.

<p>(A) NK activity. Groups of C57BL/6 mice were vaccinated with irradiated B16-mBD2, B16-p, or B16, respectively, and one week later, their splenic mononuclear cells were isolated and used as NK effector cells. The NK effector cells were mixed with Yac-1 cells at the indicated ratios for four hours, and the cytotoxicity of NK effectors against Yac-1 was determined by LDH assays. (B, C) CTL response. Additional splenic mononuclear cells were challenged with inactivated B16 cells <i>in vitro</i>, and the lymphocytes were purified and used as CTL effectors. The cytotoxicity of CTL effectors against B16 (B) or syngeneic irrelavant control Hepa1–6 (C) was determined by LDH assays. Data are expressed as mean % ± SD of each group of mice (n = 3) from three independent experiments. (D) Cytokine responses. The supernatants of cultured mixture of splenic mononuclear cells and inactivated B16 cells were harvested, and the concentrations of indicated cytokines were determined by ELISA assays. Data are expressed as mean ± SD of each group of mice (n = 3) from three separate experiments. (E) Spontaneous and inducible MHC-I expression in B16 cell. B16 cells were treated with, or without, 350 pg/mL of IFN-γ for 4 or 24 h, respectively and the levels of H-2K^b, H-2D^b expression on B16 cells were characterized by flow cytometry analysis. Data shown are representative histographes of each group of cells from five separate experiments. Much more frequent of Kb⁺ and Db⁺ B16 cells were observed following treatment with IFN-γ for 24 h (data not shown).