Soluble C5b-9 (sC5b-9) in Pediatrics-A Clinical Assessment

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.