urine dendritic cells (DCs) of the established JAWS II cell line were transduced with a retroviral vector carrying murine interleukin 12 (IL-12) genes (JAWS II/IL-12 cells). The JAWS II/IL-12 cells produced ≈9-18 ng IL-12 protein/ml/5x105 cells/48 h and displayed an increased CD80 and CD86 expression as well as major histocompatibility complex antigen up-regulation. The JAWS II/IL-12 cells were used as a temporary source of IL-12 for the immunotherapy of C57BL/6 mice bearing transplantable murine colon carcinoma (MC38). The cell vaccines were administered according to different application schedules into the vicinity of subcutaneously growing palpable MC38 tumors. The JAWS II/IL-12 cells were delivered alone or in combination with JAWS II cells pulsed with MC38 tumor cell lysate (TAg) (JAWS II/TAg cells). The anti-tumor response was estimated as the tumor growth delay - the time (days) required for the tumor to reach a volume of 1 cm3 (TRV), and as the increase in animal life-span (ILS). Mice treated with three consecutive injections of JAWS II/IL-12 or JAWS II/TAg cells responded with moderate tumor growth delay (up to 6.5 and 9.5 days, respectively). After the administration of the JAWS II/IL-12 and JAWS II/TAg cell combination, the TRV was prolonged up to 12.5 days and there was a long-lasting tumor growth delay. Increasing the number of DC-based vaccines to four, resulted in the ILS extension of up to 87% over the control. A similar effect was observed when the vaccine containing the combination of both DC components was delivered prior to the three consecutive injections of JAWS II/IL-12 or JAWS II/TAg cells administered independently. The JAWS II/IL-12 cell vaccination of MC38 tumor-bearing mice was accompanied by an increased percentage of IFN-γ-producing CD8+ spleen cells. Concluding, JAWS II DCs transduced with IL-12 genes could be used as an adjuvant vaccine for immuno- as well as combined immuno-chemotherapy of experimental tumors.

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