Ha S J, Lee S B, Kim C M, Shin H S, Sung Y C
Department of Life Science, Pohang University of Science and Technology, Center for Biofunctional Molecules, Pohang, Kyungbuk, South Korea.
Immunology. 1998 Sep;95(1):156-63. doi: 10.1046/j.1365-2567.1998.00579.x.
In order to study the mechanism of interleukin-12 (IL-12) antitumour activity, RH7777 rat hepatoma cells were engineered to express mouse IL-12 (mIL-12) (RH7777/mIL-12) under the tight control of doxycycline (dox). The production of the mIL-12 protein was regulated by the concentration of dox that was present in the culture medium. RH7777/mIL-12 cells appeared to have the same tumorigenic activity as did parental RH7777 cells, when subcutaneously injected into syngeneic rat (BUF/N) in the absence of dox. However, the tumorigenicity of RH7777/mIL-12, but not RH7777, cells were significantly decreased when dox was administrated to the animals. In addition, established tumours of RH7777/mIL-12 cells gradually disappeared upon the induction of mIL-12 by dox. To elucidate the kinetic profile of immune cells involved in the mIL-12-induced tumour regression, both histological and immunohistochemical analyses were performed 1, 3 and 14 days after the dox treatment on rats bearing tumours that were approximately 0. 5 cm in diameter. Tumour-infiltrating macrophages began to appear at the tumour site one day after dox treatment. As time elapsed, the number of tumour infiltrates including CD4+, CD8+, natural killer (NK) cells and macrophages gradually increased. In particular, CD8+ and NK cells constituted the major population of the tumour-infiltrated cells. Furthermore, it was found that resting peritoneal macrophages (PM) from rats were chemoattracted in response to mIL-12. The effects of mIL-12 on PM chemotaxis were reproducibly observed in concentrations as low as 0.1 ng/ml. These findings suggest that IL-12 can directly recruit macrophages into tumour sites which, in turn, leads to a broad and intense immunological response against tumour.
为了研究白细胞介素 - 12（IL - 12）的抗肿瘤活性机制，对RH7777大鼠肝癌细胞进行基因工程改造，使其在强力霉素（dox）的严格调控下表达小鼠IL - 12（mIL - 12）（RH7777/mIL - 12）。mIL - 12蛋白的产生受培养基中dox浓度的调节。当在无dox的情况下皮下注射到同基因大鼠（BUF/N）体内时，RH7777/mIL - 12细胞似乎具有与亲代RH7777细胞相同的致瘤活性。然而，当给动物施用dox时，RH7777/mIL - 12细胞的致瘤性显著降低，而RH7777细胞则不然。此外，在通过dox诱导mIL - 12后，RH7777/mIL - 12细胞形成的肿瘤逐渐消失。为了阐明参与mIL - 12诱导的肿瘤消退的免疫细胞的动力学特征，在对直径约0.5 cm的荷瘤大鼠进行dox治疗后的第1、3和14天进行了组织学和免疫组织化学分析。dox治疗一天后，肿瘤浸润巨噬细胞开始出现在肿瘤部位。随着时间的推移，包括CD4 +、CD8 +、自然杀伤（NK）细胞和巨噬细胞在内的肿瘤浸润细胞数量逐渐增加。特别是，CD8 +和NK细胞构成了肿瘤浸润细胞的主要群体。此外，还发现来自大鼠的静息腹腔巨噬细胞（PM）对mIL - 12有趋化反应。在低至0.1 ng/ml的浓度下可重复观察到mIL - 12对PM趋化性的影响。这些发现表明，IL - 12可直接将巨噬细胞募集到肿瘤部位，进而引发针对肿瘤的广泛而强烈的免疫反应。
