An enzyme-linked immunosorbent assay applicable to screen blood donors for IgA deficiency.

BACKGROUND AND OBJECTIVE: In order to build panels of IgA deficient blood donors, an assay is described that is sensitive, inexpensive and easily adaptable to the automated sample processors and turnaround times of blood banks.

DESIGN AND METHODS: We developed a two-step enzyme-linked immunosorbent assay (ELISA) carried out in microwell plates coated with rabbit anti-human IgA antibody. Captured IgA was revealed with the same antibody conjugated to horseradish-peroxidase. The assay was adapted to the automatic pipetting system and ELISA processors used in routine blood donor screening.

RESULTS: The assay sensitivity was 0.1 microg/mL. Intra-assay coefficient of variation (CV) for IgA concentrations between 0.1 and 100 microg/mL ranged from 0.69% to 3.80%. The median interassay CV was 3.05% (range: 1.2-7.9%). Coated plates can be stored frozen for at least 3 months without any loss in performance. The assay takes around 80 min to be performed. By using this ELISA we found 32 IgA-deficient individuals among 20,000 blood donors (prevalence 1:625).

INTERPRETATION AND CONCLUSIONS: The ELISA has a good sensitivity, is reproducible, precise and timesaving. It is easily adaptable to the automated sample processors and operating procedures used in blood banks. This facilitates the building of panels of IgA-deficient blood donors.