Discrepancies between two immunoassays for the determination of MPO and PR3 autoantibodies

Area of Science:

• Clinical immunology
• Autoimmune disease diagnostics
• Laboratory medicine

Background:

• Anti-neutrophil cytoplasmic antibody (ANCA) testing, including myeloperoxidase (MPO) and proteinase 3 (PR3) autoantibodies, is crucial for diagnosing autoimmune diseases like small-vessel vasculitis.
• Variability in diagnostic test results can impact patient care and disease management.

Purpose of the Study:

• To compare the performance of two automated immunoassay platforms for detecting MPO- and PR3-ANCA autoantibodies.
• To assess the concordance and correlation between different assay methods across multiple laboratory facilities.

Main Methods:

• Analysis of 117 serum samples for MPO and PR3 autoantibodies using two distinct automated immunoassay systems: INOVA QUANTA Lite® IgG and Bio-Plex® 2200 Vasculitis Panel.
• Qualitative and quantitative comparisons of assay results were performed between the INOVA and Bio-Plex methods, as well as between two facilities utilizing the INOVA assay.

Main Results:

• High concordance (97.2% for MPO, 94.4% for PR3) and correlation (R²=0.973 for MPO, R²=0.935 for PR3) were observed between INOVA QUANTA Lite® assays performed at two different facilities.
• Conversely, poor concordance was found between the INOVA QUANTA Lite® and Bio-Plex® methods, with results of 70.4% for MPO and 76.5% for PR3.

Conclusions:

• Significant discrepancies exist between the INOVA QUANTA Lite® and Bio-Plex® automated immunoassay methods for measuring MPO- and PR3-ANCA.
• Clinical laboratories and healthcare providers should be aware of these performance differences when interpreting MPO-ANCA and PR3-ANCA results to ensure accurate diagnosis and patient management.