Natural rubber latex-specific IgE antibodies in non-healthcare workers: comparison of two FDA-cleared in vitro kits.
Biagini-RE; MacKenzie-BA; Bledsoe-T; Lewis-DM; Pinkerton-L
J Environ Med 1999 Jul; 1(3):147-151
Latex-specific IgE antibody immunoassays are heavily relied upon in the diagnosis of latex allergy in the United States. The goal of this study is to compare anti-latex IgE levels measured by two U.S. Food and Drug Administration (FDA)-cleared kits (CAP System and AlaSTAT Microplate) in sera obtained from employees in non-healthcare industries. Sera were obtained from 381 workers employed in several, non-healthcare industries over the past 10 years, and stored frozen. All 381 coded sera were analysed for latex-specific IgE using the Diagnostic Products Corporation microplate AlaSTAT and the Pharmacia-UpJohn CAP System. Concordance between methods and intra- and inter-assay reproducibility were evaluated. Twenty-six sera gave positive results using the AlaSTAT assay (26/381, 6.82%), while 24 yielded CAP positive results (6.30%). There were no significant differences (p = NS) between the assays' measurements of latex-specific IgE antibody levels for all 381 sera, yielding 0.28 +/- 0.19 kU L-1 and 0.34 +/- 0.59 kUA L-1, respectively. AlaSTAT and CAP assays agreed on the positive status of 9 (9/381, 2.4%) sera, and the negative status of 340 sera (340/381, 89.2%). The assays yielded discordant results on some individual sera. CAP discordant results occurred in 17/26 sera (65.4%) of AlaSTAT positive sera, while AlaSTAT discordant results were found in 15/24 (57.7%) of the CAP positive sera. The CAP System, for instance, detected 0.39-2.3 kUA l-1 (1.03 +/- 0.59, [mean +/- SD]) of latex-specific IgE in the serum from 15 individuals that were all AlaSTAT negative. In contrast, the AlaSTAT detected 0.36-1.6 kU l-1 (0.62 +/- 0.31, [mean +/- SD]) of IgE anti-latex in the serum from 17 subjects that were all CAP negative. These data indicate that the a priori seroprevalence of latex-specific sera IgE is about 6%-7% in non-healthcare workers and that the CAP and AlaSTAT assays agree on the positive or negative status of the majority of sera (91.6%). However, caution should be exercised when applying FDA-cleared in vitro assays for latex-specific sera IgE in populations known to have potentially low concentrations of latex-specific IgE antibodies, as there appears to be a finite possibility for these assays to misclassify sera as being positive or negative for latex-specific IgE antibodies.
In-vitro-studies; Allergies; Allergic-reactions; Workers; Worker-health; Analytical-processes
Raymond E. Biagini, NIOSH, Division of Biomedical and Behavioral scievce, MS C26, 4676 Columbia Parkway, Cincinnati, OH 45226, USA
DART; HELD; DSHEFS
Journal of Environmental Medicine