Fig. 4.

Induction of TAA-specific Th1 cytokines by three DC Ag-loading strategies. DCs were pulsed with either SNU899 tumor cell supernatant, stressed lysate, or irradiated tumor cells. Autologous PBLs were stimulated twice with Ag-loaded mature DCs. On day 6 after the second stimulation, production of IFN-γ, IL-2, and TNF-α by TAA-specific CD4⁺ T cells was detected by intracellular staining. a Numbers indicate the percentage of gated CD4⁺ T cells. When PBLs were stimulated by TCL-DCs, the percentage of IFN-γ and IL-2-secreting CD4⁺ T cells was higher than in other groups, whereas DC-ITC induced a higher percentage of TNF-α-secreting CD4⁺ T cells. b Number of Th1 cytokine (IFN-γ, IL-2, and TNF-α)-positive cells were assessed by flow cytometry. Compared with the DC control, TCL-DCs stimulated an effective TAA-specific T cell response, whereas DC-TCS and DC-ITC inhibited such responses. These results clearly demonstrate the efficacy of stressed lysis as a means of tumor cell preparation for DC loading. Data are mean values ± SD of triplicate determinations. Statistical comparisons were performed using Student’s t-test. *P < 0.05 vs. DC control; **P < 0.01 vs. DC control