Goodnough L T, Saito H
J Lab Clin Med. 1982 Jun;99(6):873-84.
The possibility that human PBM might specifically bind several proteins of the coagulation mechanism was studied in vitro. Purified preparations of human thrombin, AT III, TH-AT III complex, and prothrombin were radiolabeled with Na[125I] and incubated with human monocyte monolayers that had been isolated from whole blood by Ficoll-Paque sedimentation gradient and adherence to plastic tissue culture wells. Specificity of binding was determined by its suppression in the presence of excess concentrations of the appropriate nonradiolabeled protein. PBM were found to bind thrombin specifically but did not specifically bind AT III, TH-AT III complex, or prothrombin. Further characterization of thrombin binding by PBM showed that uptake was time- and temperature-dependent, saturable, and reversible, suggesting an active, receptor-mediated process. Scatchard analysis of [125I]thrombin binding in the presence of increasing concentrations of nonradiolabeled thrombin showed two populations of receptors: a high-affinity receptor with Kd = 3.4 x 10(-9) M and a low-affinity receptor with Kd = 1.3 x 10(-7) M. These studies indicate that PBM may play a role in the clearance of activated clotting factors from the circulation and serve as an experimental model to study the role of the RES as a defense against thrombosis.
在体外研究了人外周血单核细胞（PBM）可能特异性结合凝血机制中几种蛋白质的可能性。将人凝血酶、抗凝血酶III（AT III）、凝血酶-抗凝血酶III复合物（TH-AT III complex）和凝血酶原的纯化制剂用Na[125I]进行放射性标记，并与通过Ficoll-Paque沉降梯度从全血中分离并贴壁于塑料组织培养孔的人单核细胞单层一起孵育。通过在过量浓度的适当非放射性标记蛋白质存在下其结合的抑制来确定结合的特异性。发现PBM特异性结合凝血酶，但不特异性结合AT III、TH-AT III复合物或凝血酶原。对PBM与凝血酶结合的进一步表征表明，摄取是时间和温度依赖性的、可饱和的且可逆的，提示这是一个活跃的、受体介导的过程。在存在递增浓度的非放射性标记凝血酶的情况下对[125I]凝血酶结合进行Scatchard分析，结果显示有两类受体：一类高亲和力受体，解离常数（Kd）= 3.4×10(-9) M，另一类低亲和力受体，Kd = 1.3×10(-7) M。这些研究表明，PBM可能在从循环中清除活化凝血因子方面发挥作用，并可作为研究网状内皮系统（RES）作为抗血栓形成防御机制作用的实验模型。
