本试剂盒应用双抗体夹心酶标免疫分析法测定标本中sEPCR水平。用纯化的抗体包被微孔板，制成固相抗体，往包被单抗的微孔中依次加入sEPCR抗原、生物素化的抗人sEPCR抗体、HRP标记的亲和素，经过彻底洗涤后用底物TMB显色。TMB在过氧化物酶的催化下转化成蓝色，并在酸的作用下转化成最终的黄色。颜色的深浅和样品中的sEPCR呈正相关。用酶标仪在450nm波长下测定吸光度（OD值），计算样品浓度。
Intended use
This immunoassay kit allows for the specific measurement of human soluble endothelial protein C receptor, sEPCR concentrations in cell culture supernates, serum and plasma.
Introduction
The endothelial cell protein C receptor (EPCR) functions as an important regulator of the protein C anticoagulant pathway by binding protein C and enhancing activation by the thrombin-thrombomodulin complex. EPCR binds to both protein C and activated protein C (APC) with high affinity. The Endothelial Protein C Receptor (EPCR, also referred to as CCD41 or CD201) is a 25 kD Type 1 transmembrane protein expressed on endothelial cells. EPCR is a ligand for Protein C and plays an important role in augmenting Protein C activation by the thrombin-thrombomodulin complex and in regulating blood coagulation and inflammation.
A soluble form of EPCR (sEPCR) has recently been detected in normal human plasma and has been shown to bind protein C and APC with an affinity similar to that of intact membrane-bound EPCR. In healthy individuals, sEPCR circulates at a concentration of 2.5 nM, a level that can increase up to 5-fold in patients with sepsis or systemic lupus erythematosus. In contrast to membrane-bound EPCR, sEPCR inhibits protein C activation over large vessel endothelium in culture. This presumably reflects competition between the sEPCR and cell surface EPCR. sEPCR also inhibits APC anticoagulant activity, but the mechanism responsible for this inhibition remains unclear. Since EPCR interacts with the membrane-binding Gla domain of protein C, it is possible that binding to sEPCR and phospholipid is mutually exclusive. Alternatively, sEPCR could mask the factor Va-binding site on APC or alter the macromolecular substrate specificity of the enzyme by altering the conformation of the extended substrate binding pocket.
Test principle
This assay employs the quantitative sandwich enzyme immunoassay technique. A antibody specific for sEPCR has been pre-coated onto a microplate. Standards and samples are pipetted into the wells and any sEPCR present is bound by the immobilized antibody. An enzyme-linked antibody specific for sEPCR is added to the wells. Following a wash to remove any unbound antibody-enzyme reagent, a substrate solution is added to the wells and color develops in proportion to the amount of sEPCR bound in the initial step. The color development is stopped and the intensity of the color is measured.
