Screening of Canadian Blood Services donors for severe immunoglobulin A deficiency.
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Immunoglobulin A (IgA)-deficient patients with antibodies to IgA require transfusions with IgA-deficient blood components to either avoid or reduce the frequency of serious adverse reactions. To supply compatible blood components for these individuals, the Canadian Blood Services (CBS) National Testing Laboratory must initially screen and subsequently identify, after confirmatory testing at the American Red Cross (ARC), donors severely deficient in IgA (<0.05 mg/dL).The Ouchterlony double immunodiffusion assay was used as an initial screen at CBS to identify IgA-deficient donors (test sensitivity 2-4 mg/dL). Sample aliquots from these donors were then sent to the ARC for confirmatory testing using an enzyme-linked immunosorbent assay method for severe IgA deficiency (<0.05 mg/dL) and a passive hemagglutination assay to detect anti-IgA.From November 2007 to December 2008, of 54,594 samples screened initially at CBS there were 137 samples (0.251%) identified as possibly IgA deficient. Of these 137, there were 100 reports returned from ARC confirming severe IgA deficiency in 65 donors (25 female, 40 male) without detectable anti-IgA and in 35 donors (18 female, 17 male) with anti-IgA. The remaining 37 donors had IgA levels of more than 0.05 mg/dL.Results from the ARC confirmed a frequency of 1 in 546 in the CBS' blood donor population for severe IgA deficiency (<0.05 mg/dL), 1 in 840 for those without anti-IgA, and 1 in 1560 for those with antibody. Donors repeatedly confirmed as severely IgA deficient without anti-IgA were considered eligible for the CBS IgA-deficient donor registry program.
