Induction of helper T-cell 1-dominant state by an immunotherapeutic agent OK-432, 5-fluorouracil and radiation: Involvement of suppressor of cytokine signaling −1 and −3.

Proc Amer Assoc Cancer Res, Volume 47, 2006 5564 Background and objective: We have reported that the therapy by an immunotherapeutic agent OK-432 and 5-fluorouracil (FU) in combination with radiation exhibits a marked therapeutic effect in the patients with head and neck cancer. Although it is important in anti-cancer immunity to polarize T-cell response to helper T-cell 1 (Th1)-dominant state, CD4+T cells are able to differentiate to Th2 as well as to regulatory T cells (Treg), and produce interleukin (IL)-10 and transforming growth factor (TGF)-β, which decrease anti-cancer immunity. In the current study, we conducted the in vitro study to examine the effect of 5-FU and X-irradiation in the OK-432-induced cytokine production and expression of the molecules related to cytokine balance. Methods: Human peripheral blood mononuclear cells (PBMCs) were stimulated with OK-432 (1μg/ml), 5-FU (5μg/ml) or X-ray (2Gy). Twenty-four hours later, cytokines in the supernatants were measured by ELISA, expression of the genes for T-bet, GATA-3 and Foxp3 which are pivotal transcription factors for Th1, Th2 and Treg, respectively, and for suppressor of cytokine signaling (SOCS)-1 and SOCS-3 which are negative regulators for cytokine signaling, on the PBMCs, was evaluated by reverse transcription-polymerase chain reaction. Results: Stimulation of PBMCs with OK-432 induced Th1-type cytokines (interferon-γ, tumor necrosis factor-α, IL-12, IL-18) as well as IL-10 and TGF-β. When PBMCs were stimulated by 5-FU and/or X-ray in combination with OK-432, production of IL-10 and TGF-β was significantly inhibited. No significant change in the production of Th1-type cytokines was observed. Although OK-432 enhanced the expression of the genes encoding T-bet, GATA-3 and Foxp3, 5-FU and X-irradiation inhibited the increased expression of GATA-3 and Foxp3 genes but not of T-bet gene. Gene expression of negative regulators, SOCS-1 and SOCS-3, was augmented by OK-432, however, this was also inhibited by 5-FU and X-irradiation. OK-432-induced IL-10 and TGF-β, but not Th1-type cytokines, was significantly reduced by addition of antisense oligonucleotide for SOCS-1 or that for SOCS-3. Conclusions: Radiation and 5-FU induce Th1-dominant state by inhibiting the OK-432-induced production of IL-10 and TGF-β mediated by regulation of negative regulators, SOCS-1 and SOCS-3, and are strongly suggested to increase anti-cancer immunity.