Incidence of gammopathies in long-term plasmapheresis donors at Canadian Blood Services.

BACKGROUND: To investigate the long-term consequences of repeated plasmapheresis on donor health, their donation histories and demographic data were reviewed to determine the frequency of development of monoclonal (Mc) gammopathies or other gamma globulin abnormalities (OGGAs). STUDY DESIGN AND METHODS: Samples from apheresis plasma donors collected at Canadian Blood Services were tested initially and every 4 months for total protein (TP) followed by serum protein electrophoresis (SPE). Out-of-range samples or those showing abnormal band patterns were forwarded to a hospital laboratory for additional investigation. RESULTS: Of 52,972 donors who donated 471,446 apheresis plasmas over 9 years, 89,490 samples were sent for TP and SPE testing. Of 3005 samples forwarded for further investigation, abnormal immunofixation electrophoresis (IFE) results were found in 209 (0.4%) donors, 85 from first-time (FT) and 124 from repeat (RPT) plasma donors during participation in the program. There were 167 donors with Mc gammopathies (73 FT, 94 RPT) and 42 with OGGAs (12 FT, 30 RPT). FT or RPT donors with Mc gammopathies or OGGAs were significantly older than those with normal SPEs. RPT donors with Mc gammopathies or OGGAs also had a longer donation period than donors with normal SPEs. CONCLUSIONS: The incidence of Mc gammopathies (2.41 per 1000 donors) did not significantly increase from 2004 to 2012. Older donors had a higher incidence of Mc gammopathies and longer donation periods than their healthy counterparts. Overall, gammopathy rates were below those reported over the same age range in the general population.

Evaluation of particle gel immunoassays for the detection of severe immunoglobulin A deficiency and anti-human immunoglobulin A antibodies.

BACKGROUND: Immunoglobulin A (IgA)-deficient patients with anti-IgA (Ab) require transfusions using blood components with less than 0.05 mg IgA/dL as they are known to be safe for these patients. Identification of severely IgA-deficient (IgA SD) donors involved preliminary screening by the Ouchterlony double immunodiffusion assay followed by confirmatory testing at the required level of sensitivity for IgA and Ab at an external reference laboratory. Two in vitro particle gel immunoassays (ID-PaGIA IgA deficiency test and anti-IgA test) were also evaluated for their suitability in identifying IgA SD individuals and determining their Ab status. STUDY DESIGN AND METHODS: Samples from 198 donors and 36 patients, subjected to confirmatory testing for IgA SD and Ab over a 2-year period, were also evaluated using the ID-PaGIA kits. RESULTS: DiaMed test sensitivity and specificity for detection of IgA SD in donors was 98% whereas for Ab, test sensitivity was 91% at a specificity of 94%. In patients, sensitivity was 94% for IgA SD and 67% for Ab, both tests at a specificity of 100%. CONCLUSIONS: The ID-PaGIA IgA deficiency test was a sensitive and specific tool for identifying IgA SD donors or patients. Sensitivity of the Ab test was high for donors but reduced for patients and of high specificity in both groups. Further studies with patients are needed to confirm this latter observation. Implementation of these tests would make it possible to supply appropriate products from IgA SD donors to prevent anaphylactic transfusion reactions in patients.

Screening of Canadian Blood Services donors for severe immunoglobulin A deficiency.

BACKGROUND: 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). STUDY DESIGN AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Flow cytometric determination of residual white blood cell levels in preserved samples from leukoreduced blood products.

BACKGROUND: In preparation for a proposed consolidated testing service, Canadian Blood Services undertook the evaluation of a commercial test kit for the enumeration by flow cytometry of residual white blood cells (rWBCs) present in preserved samples recovered from leukoreduced (LR) blood and platelet products. STUDY DESIGN AND METHODS: The stability of preserved WBCs, the equivalency of WBCs used for spiking, test method precision, specificity, reliability, accuracy, and sensitivity were investigated. For comparative purposes, WBC counts were also determined by Nageotte as well as by flow cytometry. RESULTS: WBCs were stable up to 4 weeks at room temperature for all components by either method. Within methods, no differences were observed due to the source of WBC used for spiking purposes. By either method, test precision was acceptable (<20% coefficient of variation) and of similar reliability at a target value of 10 +/- 5 WBCs per microL. The flow cytometric method was shown to be more specific and accurate than the Nageotte method. Sensitivity by either method was 0.1 WBCs per microL. On average, Nageotte counts were lower than those observed by flow cytometry. CONCLUSIONS: These results demonstrate that WBCs in WBC stabilizing solution-treated samples from LR blood components were stabilized up to 4 weeks at room temperature and that rWBC determinations made with a WBC enumeration kit by flow cytometry have the required precision, specificity, reliability, and accuracy in the relevant test range. This validated WBC stabilization and flow cytometric counting method is considered acceptable as part of a quality control program for leukoreduced blood products.