Farrar W L, Elgert K D, Foo A S
J Immunol. 1981 Dec;127(6):2339-44.
The factor(s) derived from fibrosarcoma-induced suppressor T cells was sensitive to pronase and neuraminidase, but not to trypsin, beta-galactosidase, DNase, or RNase. Protein and RNA, but not DNA, synthesis were required to mediate suppression. Suppressor T cell-derived factor(s) could be precipitated by a 50% saturated ammonium sulfate (SAS) solution. The 50% SAS fraction inhibited both in vitro and in vivo spleen cell blastogenesis, whereas the 80% and unprecipitated fractions had no inhibitory activity. Using Sephadex G-200 chromatography, the 2nd protein fraction (fraction II) contained an inhibitor of both DNA polymerases (IDP) and DNA synthesis (IDS) activity, which possessed no cytotoxic activity. In vitro DNA polymerase alpha activity was suppressed by fraction II, whereas DNA polymerase beta and gamma activities remained unchanged. Molecular weight of IDP/IDS, as determined by Sephadex G-200 gel filtration chromatography, was approximately 14,500. Attempts to separate IDP/IDS activities found in fraction II by anion-exchange chromatography and slab gel electrophoresis were not successful, which suggested that the 2 activities were the same or very similar molecules.
源自纤维肉瘤诱导的抑制性T细胞的因子对链霉蛋白酶和神经氨酸酶敏感，但对胰蛋白酶、β-半乳糖苷酶、脱氧核糖核酸酶或核糖核酸酶不敏感。介导抑制作用需要蛋白质和RNA的合成，但不需要DNA的合成。抑制性T细胞衍生因子可被50%饱和硫酸铵（SAS）溶液沉淀。50% SAS组分在体外和体内均抑制脾细胞的增殖，而80%组分和未沉淀组分无抑制活性。使用葡聚糖G-200柱色谱法，第二个蛋白质组分（组分II）含有一种DNA聚合酶抑制剂（IDP）和DNA合成（IDS）活性，且无细胞毒性活性。体外实验中，组分II抑制DNA聚合酶α活性，而DNA聚合酶β和γ活性保持不变。通过葡聚糖G-200凝胶过滤色谱法测定，IDP/IDS的分子量约为14,500。尝试通过阴离子交换色谱法和平板凝胶电泳法分离组分II中发现的IDP/IDS活性未成功，这表明这两种活性是相同或非常相似的分子。
