Arvieux J, Roussel B, Pouzol P, Colomb M G
Laboratories d'Immunologie, Hôpital Sud, Grenoble, France.
Thromb Haemost. 1993 Aug 2;70(2):336-41.
Previously developed murine monoclonal antibodies (MAbs) to human beta 2-glycoprotein I (beta 2 GPI), a plasma protein required for the binding of anti-phospholipid antibodies, were studied for anti-platelet reactivity and influence on platelet function. The six MAbs (IgG1 isotype) tested interacted with both intact and fixed platelets in a beta 2 GPI-dependent manner. Carbamylated beta 2 GPI was still recognized by MAbs but was unable to mediate platelet-antibody binding. MAbs induced aggregation and secretion responses of platelets in platelet-rich plasma (PRP) and whole blood, provided subthreshold concentrations of weak agonists (i.e. ADP or adrenaline) were added. When aggregation in PRP was evaluated by a counting technique instead of turbidometrically, the sole addition of MAbs led to a rapid fall in single platelets. Triggering gel-filtered platelets with MAbs together with beta 2 GPI, but not its carbamylated form, led to platelet activation after a lag time, as monitored by aggregometry, measurements of ATP and beta-thromboglobulin secretion and calcium mobilization. F(ab')2 fragments of one of the MAbs failed to activate platelets but inhibited the responses to the whole antibody. This process thus depends on MAbs binding to platelets through both Fab and Fc domains, as confirmed by the suppression of platelet responses upon pretreatment with the anti-Fc gamma RII MAb IV.3. Aggregation and secretion induced by MAbs plus beta 2 GPI did not require exogenous fibrinogen and were variably inhibited in the presence of acetyl salicylic acid, apyrase or Ca2+, depending on the concentrations used for the two proteins.(ABSTRACT TRUNCATED AT 250 WORDS)
此前已开发出针对人β2糖蛋白I（β2GPI）的鼠单克隆抗体（MAb），β2GPI是抗磷脂抗体结合所需的一种血浆蛋白，本研究对其抗血小板反应性及对血小板功能的影响进行了探究。所测试的六种MAb（IgG1亚型）以β2GPI依赖性方式与完整和固定的血小板相互作用。氨甲酰化的β2GPI仍能被MAb识别，但无法介导血小板与抗体的结合。若添加亚阈值浓度的弱激动剂（即ADP或肾上腺素），MAb可在富血小板血浆（PRP）和全血中诱导血小板的聚集和分泌反应。当通过计数技术而非比浊法评估PRP中的聚集时，仅添加MAb会导致单个血小板迅速减少。用MAb与β2GPI（而非其氨甲酰化形式）一起触发凝胶过滤血小板，经聚集测定、ATP测量、β-血小板球蛋白分泌及钙动员监测，会在延迟一段时间后导致血小板活化。其中一种MAb的F(ab')2片段无法激活血小板，但可抑制对完整抗体的反应。正如用抗FcγRII MAb IV.3预处理后血小板反应受到抑制所证实的那样，此过程依赖于MAb通过Fab和Fc结构域与血小板结合。MAb加β2GPI诱导的聚集和分泌不需要外源性纤维蛋白原，并且在乙酰水杨酸、腺苷三磷酸双磷酸酶或Ca2+存在时会受到不同程度的抑制，这取决于两种蛋白所使用的浓度。（摘要截取自250词）
