Development and validation of a fluorescent microsphere immunoassay for anti-IgA

Area of Science:

• Immunology
• Transfusion Medicine

Background:

• Individuals with immunoglobulin A (IgA) deficiency are at risk of severe anaphylactic transfusion reactions.
• The presence of IgG anti-IgA antibodies is a key indicator for identifying at-risk patients.

Purpose of the Study:

• To develop and validate a novel fluorescent immunoassay for the detection of IgG anti-IgA antibodies.
• To assess the assay's sensitivity, reproducibility, and clinical utility in identifying individuals susceptible to transfusion reactions.

Main Methods:

• Development of an immunoassay utilizing polyclonal IgA coupled to fluorescent microspheres as an immunosorbent.
• Detection of anti-IgA antibodies using phycoerythrin-labeled anti-IgG.
• Assay calibration using a reference serum containing anti-IgA and validation through dose-response and inhibition studies.

Main Results:

• The fluorescent immunoassay demonstrated positive responses at high dilutions, indicating high sensitivity.
• Inhibition studies confirmed specificity, with no inhibition by IgA-deficient serum and complete inhibition by soluble IgA.
• Clinical testing across over 90 assays showed a coefficient of variation (CV) of 13.6% for internal controls, demonstrating reproducibility.

Conclusions:

• The developed fluorescent immunoassay is a rapid, reproducible, and sensitive method for detecting low concentrations of IgG anti-IgA.
• This assay can effectively identify individuals at risk of anaphylactic transfusion reactions, aiding in transfusion safety.