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Published on: January 29, 2014
Soluble C5b-9 (sC5b-9) in Pediatrics-A Clinical Assessment
Ridwan B Ibrahim1,2, Radwa Almamoun1, Sarah E Sartain3
1Department of Pathology and Immunology, Baylor College of Medicine, Houston, Texas, USA.
Insights
The Quidel Microvue sC5b-9 Plus assay accurately measures soluble C5b-9 (sC5b-9) levels, aiding in diagnosing complement-mediated inflammatory conditions. This assay shows clinical utility for monitoring complement activation in patients.
Area of Science:
- Immunology
- Biochemistry
- Clinical Diagnostics
Background:
- Elevated soluble C5b-9 (sC5b-9) levels indicate complement activation and are linked to poor outcomes in inflammatory diseases.
- Newer therapies like eculizumab and ravulizumab necessitate reliable diagnostic and monitoring tools for complement-mediated conditions.
Purpose of the Study:
- To evaluate the analytical and clinical performance of the Quidel Microvue sC5b-9 Plus enzyme immunoassay.
- To establish reference intervals and assess the assay's utility in patient cohorts with complement-related disorders.
Main Methods:
- Analytical validation included precision, linearity, interference, and correlation with a reference laboratory.
- Clinical performance was assessed using plasma from patients with transplant-associated thrombotic microangiopathy, reduced ADAMTS13 activity, and acquired Von-Willebrand disease.
- Reference intervals were determined using healthy donor samples.
Main Results:
- The sC5b-9 assay demonstrated acceptable precision, linearity (12.6-160.66 ng/mL), and strong correlation (R=0.96) with a reference laboratory.
- The established reference range was ≤268.0 ng/mL.
- Elevated sC5b-9 levels were observed in patient cohorts, indicating complement activation.
Conclusions:
- The Quidel Microvue sC5b-9 Plus EIA exhibits adequate analytical performance and clinical usefulness for monitoring complement activation.
- Further research is recommended to correlate sC5b-9 levels with other complement activation markers.
Background:
The soluble C5b-9 (sC5b-9) is a soluble form of the Terminal Complement Complex (TCC) that is released into the circulation with elevated levels, associated with increased morbidity and mortality in patients with complement-mediated inflammatory conditions. With the advent of eculizumab and ravulizumab, proper testing for diagnoses and therapeutic monitoring is warranted.
Methods:
We evaluated both the analytical and clinical performance of the Quidel Microvue sC5b-9 Plus enzyme immunoassay. Analytical performance was evaluated with precision, linearity, interference studies, and correlation with a reference laboratory. Reference intervals were established using control donor samples [n = 26; median age 18.5 years (range 2-59)]. Clinical performance of the assay was assessed using plasma samples of patients who (i) developed transplant-associated thrombotic microangiopathy [n = 10; median age 14 years (range 3-19)], (ii) had reduced ADAMTS13 activity [n = 6; median age 16 years (range 9-18)], and (iii) developed acquired Von-Willebrand disease [n = 10; median age 18.5 years (range 0.5-18)].
Results:
The assay showed acceptable intra and inter-precision at both low and high levels. Linearity ranged from 12.6 to 160.66 ng/mL, while accuracy and method correlation studies with a reference laboratory yielded a correlation coefficient (R) of 0.96. The reference range in control donors was established at ≤ 268.0 ng/mL. Clinical performance of the assay in patients' plasma revealed elevated sC5b-9 levels suggesting complement activation in these patient cohorts compared with control levels.
Conclusion:
The Quidel Microvue sC5b-9 plus EIA assay demonstrated acceptable analytical performance and clinical utility for monitoring complement activation in patients. Further studies are needed to correlate sC5b-9 levels with existing markers of complement activation.
