Jeanneau C, Sultan Y
Laboratoire d'Hémostase et'INSERM U 152, Hôpital Cochin, Paris, France.
Thromb Haemost. 1988 Jun 16;59(3):529-34.
Two approaches were used to identify and characterize the presence of tissue plasminogen activator (t-PA) in megakaryocytes and platelets. We investigated the fibrinolytic activity of human megakaryocytes (MK) and platelets. The presence of t-PA antigen in megakaryocytes and platelets was demonstrated using immunocytochemical techniques and polyclonal or monoclonal antibodies specific for t-PA. When cells were applied to fibrin plates, lysis zones developed around isolated human megakaryocytes, whereas no fibrinolytic activity appeared when either intact washed platelets or platelet lysate were deposited. After SDS-PAGE of platelet and MK extracts (Triton X-100) immunoblotting and peroxidase staining identified t-PA antigen in several bands. Zymographic analysis of SDS-PAGE carried out on fibrin film overlays identified one or two zones corresponding to free or complexed t-PA. These results indicate that t-PA is present in platelets as well as in the precursor cells, however, in platelets, t-PA may not be immediately available for plasminogen activation and fibrin degradation. From our findings and from previous work of others, it appears that platelets may either activate or inhibit the fibrinolytic system. Therefore the conditions of plasminogen activation by platelet t-PA and plasmin inhibition by platelet alpha 2-antiplasmin or other inhibitors have to be precised before the role of platelets in clot dissolution is understood. The physiological role of platelets in fibrinolysis and clot dissolution remains unclear. In 1953, the antifibrinolytic activity of blood platelets was demonstrated and in the early 1960's a fibrinolytic activity, increasing with platelet concentration in the experimental system, was shown.(ABSTRACT TRUNCATED AT 250 WORDS)
采用两种方法来鉴定和表征巨核细胞和血小板中组织纤溶酶原激活物（t-PA）的存在情况。我们研究了人巨核细胞（MK）和血小板的纤溶活性。使用免疫细胞化学技术以及针对t-PA的多克隆或单克隆抗体，证实了巨核细胞和血小板中存在t-PA抗原。当将细胞应用于纤维蛋白平板时，在分离出的人巨核细胞周围形成了溶解区，而当放置完整的洗涤血小板或血小板裂解物时，则未出现纤溶活性。对血小板和MK提取物（Triton X-100）进行SDS-PAGE后，免疫印迹和过氧化物酶染色在几条带中鉴定出了t-PA抗原。在纤维蛋白膜覆盖物上进行的SDS-PAGE酶谱分析确定了一个或两个与游离或复合t-PA相对应的区域。这些结果表明，t-PA存在于血小板以及前体细胞中，然而，在血小板中，t-PA可能无法立即用于激活纤溶酶原和降解纤维蛋白。从我们的研究结果以及其他人之前的工作来看，血小板似乎既可以激活也可以抑制纤溶系统。因此，在了解血小板在凝块溶解中的作用之前，必须明确血小板t-PA激活纤溶酶原以及血小板α2-抗纤溶酶或其他抑制剂抑制纤溶酶的条件。血小板在纤维蛋白溶解和凝块溶解中的生理作用仍不清楚。1953年，证实了血小板的抗纤溶活性，并且在20世纪60年代早期，显示出一种随实验系统中血小板浓度增加的纤溶活性。（摘要截短于250词）
