Martinotti A, Stoppacciaro A, Vagliani M, Melani C, Spreafico F, Wysocka M, Parmiani G, Trinchieri G, Colombo M P
Division of Experimental Oncology D, Istituto Nationale per lo Studio e la Cura dei Tumori, Milano, Italy.
Eur J Immunol. 1995 Jan;25(1):137-46. doi: 10.1002/eji.1830250124.
Retroviral-mediated cytokine gene transfer into tumor cells is a highly effective way of inducing tumor inhibition and immunity. We analyzed the tumorigenicity of C-26 murine colon carcinoma cells transduced with genes encoding the two subunits of murine interleukin-12 (IL-12) in a polycistronic retroviral vector and selected for resistance to G418 and for IL-12 production (30-80 pg/ml). BALB/c mice injected s.c., i.v. and intrasplenically with C-26/IL-12 cells from three different IL-12-producing clones showed delayed tumor onset as compared with mice injected with control NeoR-transduced or parental tumor cells. Although C-26/IL-12 tumor-bearing mice eventually died of lung metastasis, their survival time was twice as long as that of mice injected with control cells. In experiments with mice selectively depleted of natural killer (NK) cells before tumor cell injection, the time of tumor onset and survival of mice injected with C-26/IL-12 s.c. and i.v., respectively, was reduced. CD8+ T cell depletion had no effect on latency or survival, whereas removal of CD4+ T cells led to C-26/IL-12 tumor regression in about 40% of mice. Histological and immunocytochemical characterization of leukocytes infiltrating C-26/IL-12 tumors showed only slight infiltration with few T cells in non-depleted mice but abundant infiltration by CD8+ T cells and asialo-GM1+ NK cells in tumors of mice depleted of CD4+ T cells. The lack of CD8+ T cell infiltration is not due to a CD4-mediated suppression of their activation because irradiated C-26/IL-12 cells primed for the induction of a strong cytotoxic T lymphocyte response against C-26 parental cells and induced CD8+ effector cells that protected against C-26/IL-12 in a Winn assay. Rather, the results suggest that, although C-26/IL-12 cells injected in vivo stimulate both NK and CD8+ T cells, tumor infiltration by the latter is inhibited by CD4+ T cells.
逆转录病毒介导的细胞因子基因转移到肿瘤细胞中是诱导肿瘤抑制和免疫的一种高效方法。我们分析了用多顺反子逆转录病毒载体转导编码小鼠白细胞介素-12（IL-12）两个亚基的基因的C-26小鼠结肠癌细胞的致瘤性，并选择对G418有抗性且能产生IL-12（30-80 pg/ml）的细胞。将来自三个不同产生IL-12的克隆的C-26/IL-12细胞经皮下、静脉内和脾内注射到BALB/c小鼠体内，与注射对照NeoR转导的或亲本肿瘤细胞的小鼠相比，肿瘤发生延迟。尽管携带C-26/IL-12肿瘤的小鼠最终死于肺转移，但其存活时间是注射对照细胞的小鼠的两倍。在肿瘤细胞注射前选择性清除自然杀伤（NK）细胞的小鼠实验中，经皮下和静脉内注射C-26/IL-12的小鼠的肿瘤发生时间和存活时间分别缩短。CD8 + T细胞清除对潜伏期或存活没有影响，而清除CD4 + T细胞导致约40%的小鼠C-26/IL-12肿瘤消退。对浸润C-26/IL-12肿瘤的白细胞进行组织学和免疫细胞化学表征显示，在未清除细胞的小鼠中只有少量T细胞的轻微浸润，但在清除CD4 + T细胞的小鼠的肿瘤中有大量CD8 + T细胞和去唾液酸GM1 + NK细胞浸润。缺乏CD8 + T细胞浸润不是由于CD4介导的对其激活的抑制，因为经辐照的C-26/IL-12细胞引发了针对C-26亲本细胞的强烈细胞毒性T淋巴细胞反应，并诱导了在Winn试验中能保护抵抗C-26/IL-12的CD8 + 效应细胞。相反，结果表明，尽管体内注射的C-26/IL-12细胞刺激了NK和CD8 + T细胞，但后者的肿瘤浸润受到CD4 + T细胞的抑制。
