A novel reagent for the screening of Immunoglobulin A-deficient blood donors

Immunoglobulin A (IgA) deficiency occurs in approximately 1 in 14,000 individuals in Japan. Approximately 32% harbour anti-IgA, most of which are naturally occurring and rarely cause anaphylaxis, although high-titre anti-IgA from alloimmunization can cause severe reactions. A stable supply of IgA-deficient plasma is essential for minimizing this risk. We therefore developed a novel reagent for large-scale identification of IgA-deficient donors.

Four mouse monoclonal anti-IgA-producing cell lines were established using the hybridoma method after immunizing mice with IgA protein. Purified antibodies were conjugated to carboxylate-modified polystyrene latex beads for IgA measurement using the latex agglutination method on an automated analyser. Samples with low IgA concentrations were re-tested by enzyme-linked immunosorbent assay (ELISA) for confirmation.

Adoption of a dual antibody assay design achieved a detection limit of 0.4 mg/dL, suitable for high-throughput screening. Screening of 24,977 randomly selected donor samples between February 2022 and April 2023 yielded 4 low IgA cases. IgA deficiency was verified by supplemental ELISA, which was required solely for these four samples. Three of four had IgA levels <0.05 mg/dL, which is the most common threshold for identifying IgA-deficient donors.

We have developed a new reagent for detecting IgA deficiency. The assay is automatable and appears useful for large-scale screening of blood donors.