Gene therapy for cancer using intratumoral injection of dendritic cells genetically modified to express interleukin 12

树突状细胞(DC)是一种功能强大的专职抗原提呈细胞，在细胞免疫中起着关键作用。我们先前已经证明，瘤内注射(I.T.)可以诱导特异性的抗肿瘤免疫反应。注射携带白介素12基因的骨髓来源的DC。在这项研究中，我们研究了OK-432刺激的DC是否可以以同样的方式使用。体内应用重组IL-12可使NK细胞和T细胞分泌干扰素-g，增强对肿瘤细胞的杀伤功能。然而，这些细胞因子诱导激活的巨噬细胞大量分泌一氧化氮(NO)，并似乎抑制了小鼠系统的细胞免疫。OK-432已作为一种有效的生物改良剂用于临床治疗癌症患者，并已知在体外可诱导多种细胞因子，包括干扰素-g和白介素12。在C57BL/6小鼠皮内注射MCA205肿瘤模型中，I.T.注射含或不含OK-432的骨髓来源的DC对第7天建立的肿瘤显示出微弱的抗肿瘤作用。然而，当DC、OK-432和N-硝基-L-精氨酸甲酯(L-NAME)联合作用时，观察到了强大的抗肿瘤作用，后者抑制诱导型一氧化氮合酶(INOS)介导的NO的产生。此外，该组合可从小鼠脾细胞中获得肿瘤特异性和强大的细胞毒性T淋巴细胞(CTL)。这些结果表明，由OK-432刺激的巨噬细胞和DC大量分泌的NO可强烈抑制小鼠肿瘤特异性细胞免疫功能。因此，IT。如果没有适当的调控，注射树突状细胞和OK-432可能是一种有希望的癌症免疫疗法。

Dendritic cells (DCs) are potent professional antigen presenting cells and play a key role in cellular immunity. We have previously demonstrated that specific antitumor immune response can be induced with intratumoral (I.t.) injection of bone marrow-derived DCs genetically engineered with interleukin (IL)-12 genes. In this study, we examined whether DCs stimulated with OK-432 could be used in the same manner. In vivo administration of recombinant IL-12 causes NK cells and T cells to secrete IFN-g and enhances the cytolytic functions against tumor cells. These cytokines, however, induce abundant secretion of nitric oxide (NO) from activated macrophages, and appear to suppress cellular immunity in murine system. OK-432 has been clinically used as a potent biological modifiers for treating cancer patients and is known to induce multiple cytokines including IFN-g and IL-12 in vitro. In intradermal tumor modeles using MCA205 into C57BL/6 mice, I.t. injection bone marrow-derived DCs with or without OK-432 showed marginal antitumor effects on day 7 established tumors. However, potent antitumor effects were observed when they are treated with the combination of DCs, OK-432, and N-nitro-L-arginine methyl ester (L-NAME), which inhibits inducible nitric oxide synthase (iNOS)-mediated NO production. Furthermore, tumor specific and potent cytotoxic T lymphocytes (CTLs) could be obtained from the splenocytes of the mice treated with this combination. These results suggested that tumor specific cellular immunity in mice could be strongly suppressed with NO, which is abundantly secreted by macrophages and DCs stimulated with OK-432. Thus, I.t. injection of DCs and OK-432 could be a promisingly cancer immunotherapy if NO production is properly regulated.