Irradiation-induced IL-6 suppressed IL-12 expression in tumors of hepatoma-bearing mice <i>in vivo</i> and DCs <i>in vitro</i>.

<p>IL-6 and IL-12 were measured at 1, 3, and 7 days after 10 Gy irradiation of tumors. Shown are the expressions of IL-6 and IL-12 in (a) HCa-1 and (b) MIH-2 tumors (* <i>P</i> < 0.05). BMDCs were prepared from bone marrow of mice and stimulated with LPS. (c) IL-6 expression analyzed at the indicated times by ELISA in irradiated or non-irradiated BMDCs <i>in vitro</i>. (d) IL-6R (** <i>P</i> < 0.01, <i>vs</i> No IR) and (e) sIL6R (** <i>P</i> < 0.01) were evaluated at 2 day after 10 Gy irradiation to BMDCs by FACS and ELISA, respectively. BMDCs were treated without or with IL-6 (20 ng/mL) plus LPS. (f) Down regulation of IL-12 production by IL-6 treatment in BMDCs (** <i>P</i> < 0.01). BMDCs were stimulated with LPS for activation and cultured with or without anti-IL-6 antibody (final concentration of 500 ng/mL) during the indicated times after irradiation <i>in vitro</i>. IL-6 and IL-12 were analyzed by ELISA. (g) Recovery of IL-12 production and (h) B7-1/ B7-2 expression using an anti-IL-6 antibody in irradiated-BMDCs stimulated with LPS <i>in vitro</i>. (** <i>P</i> < 0.01, * <i>P</i> < 0.05). Data are from three independent experiments.