Kobayashi H, Abe H, Ueyama T, Awaya A, Shikita M
Institute of Biological Science, Mitsui Pharmaceuticals Inc., Mobara, Japan.
Radiat Res. 1992 Mar;129(3):351-6.
Serum thymic factor (FTS) reduced mortality of mice after total-body irradiation with 7.56 Gy X rays. The radioprotective effect was achieved by daily repeated subcutaneous injections of 3-100 micrograms FTS, while doses higher than 300 micrograms/day/mouse were neither radioprotective nor toxic. Similarly, degeneration of the spleen was moderated by 3-100 micrograms FTS but not by 500 micrograms FTS in sublethally (3.78 Gy) irradiated mice. Histological examination showed that hematopoiesis was enhanced in the spleen by daily injections of 10 micrograms FTS. Spleen cells from the FTS-treated mice incorporated more [3H]thymidine in culture with or without concanavalin A. The treatment with FTS increased the production of colony-stimulating factor in the spleen as well as in peritoneal macrophage-like cells, and caused a significant increase in the number of granulocyte-macrophage colony-forming cells both in the spleen and in the femoral bone marrow. Furthermore, FTS prevented a decrease in circulating neutrophils in the sublethally irradiated mice. Prominent overshoot recovery of myelopoiesis, which occurred occasionally in sublethally irradiated mice, did not occur in the FTS-treated mice. The decrease in blood erythrocytes was also significantly reduced. These observations imply that this thymic hormone has potential as a radioprotector.
血清胸腺因子（FTS）可降低小鼠经7.56 Gy X射线全身照射后的死亡率。通过每日重复皮下注射3 - 100微克FTS可实现辐射防护作用，而剂量高于300微克/天/小鼠时既无辐射防护作用也无毒性。同样，在接受亚致死剂量（3.78 Gy）照射的小鼠中，3 - 100微克FTS可减轻脾脏的退化，而500微克FTS则无此作用。组织学检查表明，每日注射10微克FTS可增强脾脏中的造血功能。来自FTS处理小鼠的脾细胞在有或无伴刀豆球蛋白A的培养中掺入更多的[3H]胸腺嘧啶核苷。FTS处理可增加脾脏以及腹腔巨噬细胞样细胞中集落刺激因子的产生，并使脾脏和股骨骨髓中粒细胞 - 巨噬细胞集落形成细胞的数量显著增加。此外，FTS可防止亚致死剂量照射小鼠循环中性粒细胞的减少。亚致死剂量照射小鼠偶尔出现的明显的骨髓生成过度恢复现象在FTS处理的小鼠中未发生。血液红细胞的减少也显著减轻。这些观察结果表明，这种胸腺激素具有作为辐射防护剂的潜力。
