Harfenist E J, Packham M A, Mustard J F
Department of Biochemistry, University of Toronto, Ontario, Canada.
Thromb Haemost. 1988 Apr 8;59(2):319-22.
Fibrinogen is a cofactor in the aggregation of human platelets and must be added to suspensions of washed human platelets for extensive aggregation to occur in response to ADP. Although the patterns of fibrinogen binding and dissociation during platelet aggregation and deaggregation are similar for human and rabbit platelets, washed rabbit platelets aggregate extensively when stimulated with ADP even in the absence of added fibrinogen. To determine whether secreted fibrinogen was present on the surface of ADP-stimulated platelets and available to support aggregation, the binding of 125I-F(ab')2 fragments of anti-fibrinogen antibodies to formaldehyde-fixed platelets was measured. Although no fibrinogen was detected on human platelets either before or after treatment with ADP, fibrinogen was expressed on the surface of rabbit platelets after stimulation with ADP. However, this secreted fibrinogen did not dissociate during deaggregation of the platelets. Thus, the aggregation of rabbit platelets in the absence of exogenous fibrinogen may be supported by secreted fibrinogen, but a fibrinogen-independent component has not been completely ruled out.
纤维蛋白原是人类血小板聚集过程中的一种辅助因子，必须添加到洗涤过的人类血小板悬液中，才能在ADP作用下发生广泛聚集。尽管人类和兔血小板在聚集和解聚过程中纤维蛋白原的结合和解离模式相似，但即使在没有添加纤维蛋白原的情况下，洗涤过的兔血小板在受到ADP刺激时也会广泛聚集。为了确定分泌的纤维蛋白原是否存在于ADP刺激的血小板表面并可用于支持聚集，测量了抗纤维蛋白原抗体的125I-F(ab')2片段与甲醛固定血小板的结合。尽管在用ADP处理之前或之后，人类血小板上均未检测到纤维蛋白原，但兔血小板在受到ADP刺激后，其表面表达了纤维蛋白原。然而，这种分泌的纤维蛋白原在血小板解聚过程中并未解离。因此，在没有外源性纤维蛋白原的情况下，兔血小板的聚集可能由分泌的纤维蛋白原支持，但尚未完全排除与纤维蛋白原无关的成分。
