Usefulness and analytical performances of complement multiplex assay for measuring complement biomarkers in plasma

Area of Science:

• Immunology
• Biochemistry
• Clinical Diagnostics

Background:

• The complement system plays a crucial role in various diseases through complex activation pathways.
• The increasing development of complement-targeting therapies necessitates accessible tools for assessing complement activation.
• Current methods for evaluating complement activation are limited, highlighting a need for improved diagnostic approaches.

Purpose of the Study:

• To evaluate the utility of two multiplex panels for measuring complement activation fragments and intact components.
• To assess the specificity and accuracy of the assay in detecting complement deficiencies and activation states.
• To establish reference values for complement analytes and validate the assay against existing methods.

Main Methods:

• Two multiplex panels were used to quantify complement activation fragments (C4a, C3a, C5a, Bb, Ba, sC5b9) and intact components/regulators.
• Assay specificity was confirmed using complement-depleted sera and plasma from patients with complement deficiencies.
• Reference values were determined from 124 healthy donors, and activation profiles were assessed in 31 patients with complement-mediated disorders.

Main Results:

• The Complement Multiplex assay demonstrated good inter-assay reproducibility.
• The assay accurately detected all tested protein deficiencies and established assay-specific reference values.
• Measurements showed good agreement with reference methods and published data, with minor exceptions for C3, C4, and C4a.

Conclusions:

• The Complement Multiplex assay is a valuable tool for assessing complement activation and identifying deficiencies.
• Quantifying complement cleavage fragments provides insights into the activation status of the entire complement cascade.
• This assay supports the clinical evaluation of patients with complement-mediated disorders and aids in therapeutic development.