Gardiner C, Mackie I J, Machin S J
Department of Haematology, University College London, UK.
Clin Lab Haematol. 1998 Feb;20(1):41-5. doi: 10.1046/j.1365-2257.1998.00087.x.
The measurement of protein S is essential in the investigation of thrombophilia. Protein S forms a complex with C4b binding protein which exists in equilibrium with the free form but only the free form has anticoagulant cofactor activity. The accurate measurement of protein S has previously proved problematical. We have investigated the use of an ELISA method for protein S, using monoclonal antibodies directed against the free form, which can be used in parallel with polyclonal antibodies for the simultaneous assay of total protein S. The total protein S measurement was based on a well established method while the monoclonal antibody free protein S assay (mAb PS) was less complex than previous assays with no requirement for prior PEG precipitation and showed improved precision (intra-assay CV = 4.8% and 7.1%, between assay CV = 7.1% and 8.6% respectively). The mAb assay compared well with the conventional PEG precipitation ELISA for free protein S and a functional protein S assay based on the prothrombin time, in normal subjects, patients with thrombophilia, congenital protein S deficient patients or out-patients stabilized on oral anticoagulants. This assay overcomes many of the problems associated with protein S measurement and is a useful tool in the investigation of thrombophilia.
蛋白S的测定在血栓形成倾向的研究中至关重要。蛋白S与C4b结合蛋白形成复合物，该复合物与游离形式处于平衡状态，但只有游离形式具有抗凝辅因子活性。此前已证明准确测定蛋白S存在问题。我们研究了一种用于蛋白S的ELISA方法，该方法使用针对游离形式的单克隆抗体，可与多克隆抗体并行使用以同时测定总蛋白S。总蛋白S的测定基于一种成熟的方法，而单克隆抗体游离蛋白S测定法（mAb PS）比以前的测定法更简单，无需事先进行PEG沉淀，并且精密度有所提高（批内CV分别为4.8%和7.1%，批间CV分别为7.1%和8.6%）。在正常受试者、血栓形成倾向患者、先天性蛋白S缺乏患者或口服抗凝剂稳定的门诊患者中，mAb测定法与用于游离蛋白S的传统PEG沉淀ELISA以及基于凝血酶原时间的功能性蛋白S测定法相比效果良好。该测定法克服了许多与蛋白S测定相关的问题，是血栓形成倾向研究中的一种有用工具。
