Dillon B C, Estes J E, Saba T M, Blumenstock F A, Cho E, Lee S K, Lewis E P
Exp Mol Pathol. 1983 Apr;38(2):208-23. doi: 10.1016/0014-4800(83)90086-2.
Circulating fibronectin, also known as opsonic alpha 2 surface binding glycoprotein or cold-insoluble globulin, modulates phagocytosis of tissue debris, fibrin microaggregates, and gelatin-coated colloids by the reticuloendothelial (RE) system. Opsonically active fibronectin has an actin binding site and a demonstrated in vitro affinity for actin. Since actin potentially released into blood and tissue fluids following tissue injury could complex with fibronectin, the present study evaluated the effect of actin on plasma opsonic activity and Kupffer cell phagocytosis. Intravenous injection of actin did not acutely decrease plasma immunoreactive fibronectin levels although fibronectin levels increased at 6, 12, and 24 hr postinjection. However, intravenous actin injection did depress RE phagocytic activity in vivo as measured by decreased blood clearance of test colloid and impaired hepatic uptake of colloid particles as well as retention of the particles in the circulation. In vitro, preincubation of plasma with actin depressed the opsonic activity of plasma with respect to its ability to support phagocytosis, but such treatment of plasma did not alter the detection of fibronectin by immunoassay. Utilizing purified fibronectin with demonstrated opsonic activity, it was also observed that actin interaction with fibronectin would block its biological ability to enhance phagocytosis. This effect appeared to be mediated at the humoral level, since no direct depressant effect of actin on Kupffer cell function was observed. Thus, actin, if released into the blood following injury, may contribute to bioassayable opsonic fibronectin deficiency and phagocytic dysfunction, but this disturbance would remain undetectable by immunoassay of fibronectin levels.
循环纤维连接蛋白，也称为调理素α2表面结合糖蛋白或冷不溶性球蛋白，可调节网状内皮（RE）系统对组织碎片、纤维蛋白微聚体和明胶包被胶体的吞噬作用。具有调理活性的纤维连接蛋白有一个肌动蛋白结合位点，并且在体外已证实对肌动蛋白有亲和力。由于组织损伤后可能释放到血液和组织液中的肌动蛋白可与纤维连接蛋白结合，本研究评估了肌动蛋白对血浆调理活性和库普弗细胞吞噬作用的影响。静脉注射肌动蛋白并没有使血浆中免疫反应性纤维连接蛋白水平急剧下降，尽管在注射后6、12和24小时纤维连接蛋白水平有所升高。然而，静脉注射肌动蛋白确实降低了体内RE的吞噬活性，这可通过测试胶体的血液清除率降低、肝对胶体颗粒摄取受损以及颗粒在循环中的滞留来衡量。在体外，血浆与肌动蛋白预孵育会降低血浆支持吞噬作用的调理活性，但这种对血浆的处理并没有改变免疫测定法检测纤维连接蛋白的结果。利用具有已证实调理活性的纯化纤维连接蛋白，还观察到肌动蛋白与纤维连接蛋白的相互作用会阻断其增强吞噬作用的生物学能力。这种作用似乎是在体液水平介导的，因为未观察到肌动蛋白对库普弗细胞功能有直接抑制作用。因此，肌动蛋白如果在损伤后释放到血液中，可能会导致可生物测定的调理素纤维连接蛋白缺乏和吞噬功能障碍，但通过纤维连接蛋白水平的免疫测定法仍无法检测到这种干扰。
