DCs with enhanced IL-6-secretion capacity were found in tumor-bearing mice and patients. (A, B) Mice were subcutaneously inoculated with 5 × 10 5 B16-F10 cells, and mice without tumor inoculation were used as controls. Then, DCs from splenocytes were isolated 1 week, 2 weeks or 3 weeks later and stimulated with PBS, 5 μg/ml B16-F10-EXO or 100 ng/ml of LPS for 6 h. IL-6 production by DCs was detected by ELISA (n = 3) (A). DCs from splenocytes were isolated 3 weeks later and cultured in vitro for 6 h. Culture supernatant was collected and B16-F10 cells were cultured in this supernatant for 24 h. Then, the invasive ability of B16-F10 cells was measured (n = 5). Control indicates B16-F10 cells without any treatment (B). SN-DC PBS or SN-DC tumor denotes supernatant from DCs of healthy control mice or tumor mice, respectively. (C) Mice were intravenously injected with 100 μl of PBS or 10 μg/100 μl of B16-F10-EXO. Then, DCs from splenocytes were isolated 12 or 24 h later and cultured in vitro for 6 h. IL-6 production by DCs was detected by ELISA (n = 3). (D) Human DCs were isolated from PBMCs from healthy volunteers (n = 27) or breast tumor patients (n = 18) and cultured in vitro for 6 h with or without 100 ng/ml LPS. IL-6 production by DCs was detected by ELISA. The results are shown as the mean ± SEM of 3 independent experiments or of all detected samples. P values were generated by a 2-tail student's t -test.