Zou J P, Yamamoto N, Fujii T, Takenaka H, Kobayashi M, Herrmann S H, Wolf S F, Fujiwara H, Hamaoka T
Biomedical Research Center, Osaka University Medical School, Japan.
Int Immunol. 1995 Jul;7(7):1135-45. doi: 10.1093/intimm/7.7.1135.
Unfractionated spleen cells taken from tumor-bearing mice 2 weeks after tumor implantation contained tumor-primed T cells which produced cytokines including IL-2 and IFN-gamma when cultured in vitro. With progressive tumor growth this initial lymphokine-producing capacity decreased. Here, we investigated the ability of IL-12 to (i) restore suppressed IFN-gamma production, (ii) cause tumor regression and (ii) induce anti-tumor protective immunity. Addition of rIL-12 to spleen cell cultures from 4- to 10-week-old tumor-bearing mice resulted in a striking enhancement in the production of IFN-gamma compared with cultures of these cells in the absence of rIL-12 or of normal spleen cells in the presence of rIL-12. Five i.p. injections of rIL-12 into mice bearing s.c. tumors induced complete tumor regression. This was found when rIL-12 was given at early (1-2 weeks), intermediate (4-5 weeks) or even late (7 weeks) stages of tumor growth. Furthermore, IL-12-treated mice which rejected the primary tumor exhibited complete resistance to a rechallenge with the same tumor but did not reject a second syngenetic tumor. Immunohistochemical analyses following IL-12 treatment revealed that CD4+ and CD8+ T cells infiltrate the tumor. More importantly, IFN-gamma mRNA expression was observed in fresh tumor masses from tumor-bearing mice receiving IL-12 treatment. The importance of IFN-gamma was further demonstrated by the observation that the systemic administration of anti-IFN-gamma mAb prior to IL-12 treatment completely abrogated the anti-tumor effect of IL-12. Thus, these results indicate that administration of modest levels of rIL-12 to tumor-bearing mice results in tumor regression through mechanisms involving reversal of suppressed IFN-gamma production by anti-tumor T cells and the establishment of a tumor-specific protective immune response.
在肿瘤植入2周后从荷瘤小鼠获取的未分级脾细胞含有肿瘤致敏T细胞，这些T细胞在体外培养时可产生包括白细胞介素-2（IL-2）和γ干扰素（IFN-γ）在内的细胞因子。随着肿瘤的进展性生长，这种初始的淋巴因子产生能力下降。在此，我们研究了白细胞介素-12（IL-12）的能力：（i）恢复被抑制的IFN-γ产生，（ii）导致肿瘤消退，以及（iii）诱导抗肿瘤保护性免疫。将重组IL-12（rIL-12）添加到4至10周龄荷瘤小鼠的脾细胞培养物中，与在无rIL-12情况下培养这些细胞或在有rIL-12情况下培养正常脾细胞相比，IFN-γ的产生显著增强。对皮下接种肿瘤的小鼠进行5次腹腔注射rIL-12可诱导肿瘤完全消退。在肿瘤生长的早期（1至2周）、中期（4至5周）甚至晚期（7周）给予rIL-12时均发现了这种情况。此外，经IL-12处理后排斥原发性肿瘤的小鼠对同一肿瘤的再次攻击表现出完全抗性，但不排斥第二种同基因肿瘤。IL-12处理后的免疫组织化学分析显示，CD4 +和CD8 + T细胞浸润肿瘤。更重要的是，在接受IL-12处理的荷瘤小鼠的新鲜肿瘤块中观察到IFN-γ信使核糖核酸（mRNA）表达。在IL-12处理前全身给予抗IFN-γ单克隆抗体（mAb）可完全消除IL-12的抗肿瘤作用，这一观察结果进一步证明了IFN-γ的重要性。因此，这些结果表明，向荷瘤小鼠给予适度水平的rIL-12可通过涉及逆转抗肿瘤T细胞抑制的IFN-γ产生以及建立肿瘤特异性保护性免疫反应的机制导致肿瘤消退。
