A Clq immunosorbent assay compared with thin-layer gel filtration for measuring IgG aggregates

Area of Science:

• Immunology
• Biochemistry
• Assay Development

Background:

• Human immunoglobulin G (IgG) aggregates can activate the complement system.
• Accurate quantification of IgG aggregates is crucial for understanding immune responses and disease pathogenesis.
• Existing methods for detecting IgG aggregates have limitations in sensitivity or specificity.

Purpose of the Study:

• To develop and validate a new, highly sensitive assay for measuring C1q-binding of human IgG aggregates.
• To compare the performance of the new assay with established methods like thin-layer gel filtration and hemolysis inhibition.

Main Methods:

• Development of an enzyme-linked immunosorbent assay (ELISA) utilizing C1q-coated tubes.
• Detection of bound IgG aggregates using enzyme-linked anti-human IgG.
• Quantification of IgG aggregates using thin-layer gel filtration (13S or more, and 10S sizes).
• Measurement of complement fixation via the classic hemolysis inhibition method.

Main Results:

• The new ELISA technique demonstrates high sensitivity, detecting less than 0.01 µg of IgG aggregates per milliliter.
• Results from the new assay showed a significant positive correlation (P < 0.01) with IgG aggregate quantification by thin-layer gel filtration.
• Both the new method and gel filtration correlated significantly with the hemolysis inhibition assay for complement fixation.

Conclusions:

• The developed C1q-binding ELISA is a sensitive and reliable method for quantifying human IgG aggregates.
• This assay offers a valuable tool for immunological research and clinical diagnostics.
• The findings support the utility of this assay in assessing complement-activating properties of IgG aggregates.