Development and validation of 14 human serum protein assays on the Roche cobas® c 501

Abstract

Many laboratories rely on dedicated nephelometers and turbidimeters for the measurement of serum proteins. There are, however, a number of chemistry analyzers that offer open channel configurations for end-user applications. We developed and validated 14 human serum protein assays (α(1)-antitrypsin, α(2)-macroglobulin, albumin, apolipoproteins AI and B, complement components 3 and 4, haptoglobin, immunoglobulins A, G, and M, orosomucoid, transferrin, and transthyretin) on the Roche cobas(®) c 501. We obtained excellent precision at low, normal, and high physiologic concentrations of each protein (within-run imprecision CVs ≤2.5%, total imprecision CVs ≤3.6%). Linearity for each method was within 5% of the expected value throughout the calibration range, and method comparison studies to commercial assays from Roche or Siemens were in good agreement (r>0.975). We observed no significant interference from bilirubin (up to 414 mg/l), hemoglobin (up to 8.9 g/l), triglyceride (up to 28 g/l), or rheumatoid factor (up to 3,930 IU/ml). Calibration was stable for at least 14 days. The instrument's small reaction cell allowed us to conserve nearly 60% of our specimen and reagent volume compared with our previous system. These newly developed assays provide precise and accurate results with high throughput, but without the associated cost of a dedicated instrument.

Serum levels and genotype distribution of α1-antitrypsin in the general population

“…AAT (g/litre) and C-reactive protein (CRP, mg/litre) concentrations were determined by latex-enhanced immunoturbidimetric assay (COBAS Integra analyzer, Roche Diagnostics, Indianapolis, Indiana, USA), a robust assay with principles that are perfectly comparable to those of nephelometry 12. The interassay coefficient of variation (CV) was 3.6–4.6%; lower detection thresholds for the AAT and CRP assays were 0.21 g/litre and 1 mg/litre, respectively, and reference values were 0.9–2.0 g/litre and <8 mg/litre, respectively.…”

European Respiratory Society statement: diagnosis and treatment of pulmonary disease in α1-antitrypsin deficiency

“…Nowadays, the measurement of AAT levels in blood is mostly performed by nephelometry or, less commonly, a comparable latex-enhanced immunoturbidimetric assay (table 1) [26].…”

Comparison Of Immunonephelometric And Immunoturbidimetric Methods for Measuring Beta 2-Microglobulin: Fit for Purpose in Routine Clinical Laboratories

“…Denham et al [29] demonstrated that by their performance characteristics, the Architect ci8200 immunoturbidimetric specific protein assays are suitable for routine use, and correlate well with representative immunonephelometric assays on the Beckman Immage analyzer. In a study of Ledue et al [25], in which they evaluated the method performance characteristics of 14 serum protein analytes (alfa 1-antitrypsin, alfa 2-macroglobulin, albumin, apolipoproteins AI and B, C3, C4, haptoglobin, IgA, IgG, IgM, orosomucoid, transferrin and transthyretin) in Roche Cobas C501, they found an excellent correlation between immunonephelometric and immunoturbidimetric assays.…”

“…Immunoturbidimetric assays have been improved considerably over time. These improvements include advances in antibody purification techniques, enhancements in instrument design and function and production of new reference materials based on global standardization initiatives [22][23][24][25][26]. Additional practical advantages of immunoturbidimetric protein assays include random access analysis instead of batch testing, relatively rapid turn around time, high volume testing capability, cost reduction through consolidation of testing on a single platform, elimination of stand alone specialized analyzers, and time and effort required to maintain them [21].…”