ABSTRACT
【Objective】 To establish and evaluate a nephelometric assay for the determination of immunoglobulin A (IgA) residues in human intravenous immunoglobulin(IVIG). 【Methods】 BN ProSpec© automatic protein analyzer and its supporting immunoglobulin A determination kit (nephelometry) produced by German Siemens and the national standard of human IgA were used to establish the nephelometric assay to determine IgA residue in test products and verify the methodology. The test products include IVIG (pH4) prepared by low-temperature ethanol protein separation process and a novel IVIG prepared by chromatography. 【Results】 The average deviation of three calibration curves for IgA residues determination by the nephelometric assay were 1.08%, 0.95% and 1.54%,, and the three deviations of the quality control were 4.00%, -2.30% and -0.20%, respectively, which indicated good calibration and quality control. In the specificity test, the average recovery rates of IgA for reference substance 1 containing 100g/L maltose and reference substance 2 containing 20g/L glycine were 102.7% and 105.8%, respectively. The relative standard deviation (RSD) values of the repeatability tests of the two test products were 3.9% and 1.9%, and the RSD values of the intermediate precision test were 3.6% and 2.3%, respectively.The difference values at each time point in the durability test of test products′ storage time were all less than 10%, and the RSD values of the two test products in the durability test of kits of different batches were 2.8% and 2.2%, respectively. In the accuracy test, the average recovery rates of IVIG (pH4) added to the standard were 94.2%, 101.7% and 96.2%, respectively, and the average recovery rates of the novel IVIG added to the standard were 102.8%, 106.3% and 99.7%, respectively. The average recovery rate of the limit quantification test was 101.0%, and the RSD was 4.0%. 【Conclusion】 Nephelometric assay has the advantages of strong specificity, high precision and accuracy, good repeatability, simple and rapid operation, and automation, and can be used for the determination of IgA residue in IVIG (pH4) and novel IVIG products.
ABSTRACT
Objective To compare the results of three methods for measuring C reaction protein.Methods 100 patients were collected from our hospital,and three different methods for measuring C reaction protein were used to analyze the level of C reaction protein.Results Correlation analysis showed that the correlation between immunoturbidimetric assay and immunochromatography was higher.The differences of three methods assayed the C reaction protein were significant (P 0.05).The differences among all of test peo-ple were significant(P <0.05).Conclusion Detection of C reaction protein was important for diagnose inflammatory diseases.
ABSTRACT
Rheumatoid factor (RF) is one of the criteria used for diagnosis of rheumatoid arthritis (RA). The method that has been used in our laboratory service for many years is latex agglutination assay that gives semi-quantitative results. We are going to change from this method to nephelometry that gives continuous results. The cut-off point of RF by nephelometry, comparison of these 2 methods and the 4 supplying companies were determined. Serum samples were collected from 70 patients with RA, 22 patients with various collagen diseases and 150 blood donors or normal old people. RF values by nephelometry and 4 commercial latex agglutination assays, that were latex Alexon, Shield diagnostics, Biosyste, and Behring diagnostics, were determned and compared. The results showed that the cut-off point of RF by nephelometry was 14 IU/ml and the sensitivity and the specificity was 81% and 95% respectively. The sensitivity and the specificty of latex agglutination assays by 4 companies were 76% and 94%, 68% and 97%, 62% and 98% and 64% and 98% respectively. We concluded that nephelometry gave higher sensitivity than latex agglutination asssay and Latex Alexon had the highest sensitivity when comparing among the 4 companies.
ABSTRACT
BACKGROUND: The C-reactive protein(CRP) is one of the "acute phase" proteins and it is known to be the most sensitive indicator of the inflammatory and/or necrotic process. Traditional methods for measuring CRP are capillary precipitation assay and latex agglutination assay. However, these methods have low sensitivity and provide only qualitative results. Recently the development of specific and very sensitive assays for CRP using highly specific monoclonal antibodies for CRP have done, including radioimmunoassay, nephelometric assay(NA), and turbidimetric immunoassay(TIA). We evaluated the Hitachi 7600-110(R)(Hitachi Co., Japan) using TIA in the measurement of CRP and compared its results to those of the the LX-M(R)(Eiken Chemical Co., Japan) using NA in order to replace the Hitachi 7600-110(R) for quantitative analysis of CRP. METHODS: CRP were measured by the Hitachi 7600-110(R) using TIA and the LX-M(R) using NA in the sera from 106 patients. The relationship between results of Hitachi 7600-110(R) and LX-M(R). By performing 20 repetitive assays at three levels of CRP control serum and pooled sera, within-run, within-day, and between-day precision of the Hitachi 7600-110(R) were established. RESULTS: When the CRP value of 4.60 +/- 5.65 mg/dL by the Hitachi 7600-110(R) was compared with that of 3.71 +/- 4.32 mg/dL by the LX-M(R), coefficients of correlation of 0.994 was obtained. The regression equation was Y(Hitachi 7600-110(R)) = 1.298 X(LX-M(R)) - 0.211(r=0.994, n=106). CVs of CRP measured by Hitachi 7600-110(R) were 5.45% at 0.82 mg/dL, 1.32% at 2.39 mg/dL, and 2.37% at 4.62 mg/dL. The precision was excellent in each group. The linearity was acceptable, and sample to sample carry-over was 0.8%. CONCLUSIONS: The Hitachi 7600-110(R) using TIA, compared with the LX-M(R) using NA, showed good coefficient of correlation and excellent precision. Therefore the Hitachi 7600-110(R) can replace the LX-M for quantitative analysis of CRP.