Aplication And Development Of Cystatin C Kit

Objective:1.According to the principle of latex turbidimetric immunoassay to develop a cystatin C with intellectual property rights, provide a cheap,good performance diagnostic reagents for clinical laboratory.2.To research the variation rules of serum cystatin C (Cys C) concentration in systemic lupus nephritis(lupus nephritis) and the superiority of Cys C in reflecting renal impairment of patients with lupus nephritis than urea,creatinine (Cr) andβ2-micro globulin.Methods:1.The latex particles,125nm in diameter, was covalently attached the antibodies to the uniform microparticle to get immune microparticle firstly. And then we optimized the amount of specimens,PEG6000 and latex by observation the aggregation reaction of immune microsphere with CysC. The evaluation tests of methodology were done finally, including recovery test,repeatability test,linear range,interference test as well as comparison test with MAIKE kit.2.110 cases SLE patients of our hospital from 2010 June to December were collected, the concentration of serum Cys C,Urea,Cr,β2-MG and 24-hour urinary protein were determined respectively and the patients were classed into pure SLE group and lupus nephritis group according the 24-hour urinary protein results, lupus nephritis groups were then divided into 3 groups of light,medium and heavy based on proteinuria, and the ROC curve were use to compare each index diagnostic efficiency.RESULTS:1.The optimal amount of PEG6000,latex and sample were 2.5% 0.5% and 5ul respectively. The within- and between-run imprecision of lower,middle and high three level are 3.28%,4.96%,4.46% and 5.0%,4.98%,2.56% respectively; linear range were 0.5mg/L～7.9 mg/L, correlation coefficient was 0.999; the limit of detection was 0.3mg/L; The range of recovery rate was 97.78%--102.93%, and the average analytical recovery was 100.66%;<340ummol/L serum bilirubin,≤10mmol/L serum triglyceride and≤10g/L serum hemoglobin had no interference on Cys C concentration in this assay; correlation coefficient with Maike kit was 0.995.2.The difference of Cys C andβ2-micro globulin level of light,medium and severe proteinuria group comparative with pure SLE group have statistically significant (P<0.05); the difference of Urea and Cr level of moderate and severe lupus nephritis group comparative with pure SLE group have statistically significant (P<0.05); ROC curve display the AUC of CysC has better diagnostic efficiency than Urea,Cr and equivalent toβ2-micro globulin. CONCLUSION:1. Successful development latex enhanced turbidimetric immunoassay of Cys C, provides a new choice for clinical laboratory.2. Serum Cys C is a more sensitive marker than Urea and C r, in reflects the kidney damage and progression of patients with SLE, it is a good marker in reflected the impairment of lupus nephritis especially early renal damage.