Quantification of human complement C2 protein using an automated turbidimetric immunoassay

Area of Science:

• Immunology
• Clinical Chemistry

Background:

• Complement component C2 deficiency increases risk for systemic lupus erythematosus, infections, and atherosclerosis.
• Accurate measurement of complement components is crucial for diagnosing deficiencies and monitoring diseases.

Purpose of the Study:

• To evaluate the performance of The Binding Site's Human Complement C2 SPAPLUS® assay.
• To assess the assay's suitability for clinical diagnostics.

Main Methods:

• Assay linearity was tested across the measuring range.
• Intra- and inter-assay variability were calculated.
• Correlations with EDTA-plasma vs. serum, automated vs. radial immunodiffusion, and C2 concentration vs. CH50 activity were assessed.

Main Results:

• The assay demonstrated linearity (3.8-42.3 mg/L) with low variability (2.3%-3.8% intra-assay, 0%-3.3% inter-assay).
• Strong correlations were observed between plasma and serum measurements (R2=0.82) and between automated and radial immunodiffusion methods (R2=0.89).
• Significant differences in C2 concentrations were found between healthy controls and patient groups, including undetectable levels in homozygous C2 deficiency.

Conclusions:

• The C2 SPAPLUS® assay provides automated, rapid, and precise quantification of complement C2 protein.
• This assay can potentially replace older, less efficient methods for C2 measurement.