Quantification of circulating immune complexes by chicken anti-C4 micro ELISA

Area of Science:

• Immunology
• Clinical Chemistry
• Assay Development

Background:

• Immune complexes (IC) play a role in various autoimmune diseases and cancers.
• Quantifying C4-containing IC is crucial for understanding complement system involvement.
• Existing assays may have limitations in specificity and interference.

Purpose of the Study:

• To develop and validate a novel quantitative assay for detecting C4-containing immune complexes (CIC).
• To evaluate the assay's performance in distinguishing between patient groups and healthy individuals.

Main Methods:

• A solid-phase micro enzyme-linked immunosorbent assay (ELISA) was developed using affinity-purified chicken anti-human C4 antibody for capture.
• Protein A-alkaline phosphatase conjugate was employed for detection of the captured immune complexes.
• The assay was designed to avoid interference from rheumatoid factor and complement activation.

Main Results:

• The assay successfully quantified C4-containing immune complexes (CIC) in human sera.
• Significantly increased levels of CIC were observed in patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and lung cancer.
• Normal levels of CIC were detected in patients diagnosed with Bell's palsy, differentiating them from disease cohorts.

Conclusions:

• The developed anti-C4 micro ELISA is a reliable method for quantifying C4-containing immune complexes (CIC).
• Elevated CIC levels are associated with RA, SLE, and lung cancer, suggesting their potential as biomarkers.
• The assay shows promise for clinical diagnostics and research in immune complex-related diseases.