Loskutoff D J
J Cell Physiol. 1978 Sep;96(3):361-9. doi: 10.1002/jcp.1040960312.
The fibrinolytic activity of cells in culture varied with the type of serum employed in the growth medium. Degradation of iodinated fibrin occurred slowly when Rous sarcoma virus-transformed chick embryo fibroblasts were grown in medium containing fetal bovine serum (FBS), and rapidly when chicken serum was employed. This difference reflected the low plasminogen and high inhibitor content of FBS. The inhibitors were found to be serum macromolecules that were precipitated with ammonium sulfate or polyethylene glycol, and were inactivated by boiling or upon exposure to acidic conditions. No inhibitor activity was detected in fetuin, one of the major proteins present in FBS. Acidified FBS was similar to chicken serum in that both supported high rates of cell-mediated fibrinolytic activity. Although virally transformed hamster, mouse and chicken cells grew well in acid-treated FBS, their normal counterparts did not. Apparently, acifification resulted in the formation of materials that were toxic to normal cells. These agents rapidly blocked cellular DNA synthesis.
培养细胞的纤溶活性随生长培养基中所用血清类型的不同而变化。当劳氏肉瘤病毒转化的鸡胚成纤维细胞在含有胎牛血清（FBS）的培养基中生长时，碘化纤维蛋白的降解缓慢，而使用鸡血清时降解迅速。这种差异反映了FBS中纤溶酶原含量低和抑制剂含量高。发现这些抑制剂是血清大分子，可被硫酸铵或聚乙二醇沉淀，并通过煮沸或暴露于酸性条件而失活。在FBS中存在的主要蛋白质之一胎球蛋白中未检测到抑制剂活性。酸化的FBS与鸡血清相似，因为两者都支持高细胞介导的纤溶活性。尽管病毒转化的仓鼠、小鼠和鸡细胞在酸处理的FBS中生长良好，但它们的正常对应物却不能。显然，酸化导致形成了对正常细胞有毒的物质。这些物质迅速阻断细胞DNA合成。
