Clin Chem Lab Med. 2014 Jun;52(6):861-7. doi: 10.1515/cclm-2013-0669.
The measurement of C-reactive protein (CRP) concentrations has been of interest as a classical marker of acute phase response; in addition, it has been of particular interest in cardiovascular risk stratification where high-sensitive measurements are necessary. Since CRP is able to bind phospholipids (mainly phosphocholine) in the presence of calcium ions, we explored the possibilities of developing a high-sensitive affordable nephelometric CRP assay based on diluted soy oil emulsions.
Serum (or heparinized plasma) was mixed with Intralipid 20% in Tris-calcium buffer (pH 7.5). After 12 min of incubation at 37°C, the CRP-phospholipid complexes were measured by nephelometry (840 nm) using a BN II nephelometer (Siemens). Results (n=97) were compared with those obtained using a typical immunoturbidimetric method (Roche).
Imprecision of the functional nephelometric assay was evaluated using three human serum pools. Within-run coefficients of variation (CVs) for level 1, 2 and 3 were 6.1%, 4.7% and 4.5%, respectively, and between-run CVs were 17.6%, 18.8% and 11.3%, respectively. Good agreement was obtained between the functional nephelometric and the immunoturbidimetric CRP assay in a concentration range from 0.1 mg/L to 50 mg/L (r=0.884). A logit-log calibration curve was made between 0.056 mg/L and 1.785 mg/L. The limit of detection was 0.5 mg/L.
The functional nephelometric CRP assay allowed high-sensitive CRP determinations in serum and plasma. Since the assay is species independent, the described functional CRP assay could be used for veterinary purposes as well.
C 反应蛋白（CRP）浓度的测定一直是急性期反应的经典标志物，此外，在需要高灵敏度测量的心血管风险分层中，它也特别重要。由于 CRP 能够在钙离子存在的情况下与磷脂（主要是磷酸胆碱）结合，我们探索了基于稀释的大豆油乳液开发高灵敏度、经济实惠的散射比浊 CRP 测定法的可能性。
血清（或肝素化血浆）与 Tris-钙缓冲液（pH7.5）中的 Intralipid 20%混合。在 37°C 孵育 12 分钟后，使用 BN II 散射比浊仪（西门子）通过散射比浊法（840nm）测量 CRP-磷脂复合物。（n=97）的结果与使用典型免疫比浊法（罗氏）获得的结果进行了比较。
使用三个人类血清池评估功能散射比浊测定法的精密度。水平 1、2 和 3 的批内变异系数（CV）分别为 6.1%、4.7%和 4.5%，批间 CV 分别为 17.6%、18.8%和 11.3%。在 0.1mg/L 至 50mg/L 的浓度范围内，功能散射比浊法和免疫比浊法 CRP 测定法之间得到了良好的一致性（r=0.884）。在 0.056mg/L 至 1.785mg/L 之间制作了对数-对数校准曲线。检测限为 0.5mg/L。
功能散射比浊 CRP 测定法可用于血清和血浆中的高灵敏度 CRP 测定。由于该测定法与物种无关，因此所描述的功能 CRP 测定法也可用于兽医用途。
