Specific IgE to isocyanates: A useful diagnostic role in occupational asthma

Background: Isocyanates are the most frequent cause of occupational asthma in industrialized countries. Objective: We sought to investigate the utility of specific IgE measurement in the diagnosis of isocyanate-induced asthma. Methods: Fifty-eight of 101 patients referred for investigation were diag...

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Veröffentlicht in:Journal of allergy and clinical immunology 1998-05, Vol.101 (5), p.709-715
Hauptverfasser: Tee, Rosemary D., Cullinan, Paul, Welch, Jennifer, Burge, P.Sherwood, Newman-Taylor, Anthony J.
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Sprache:eng
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Zusammenfassung:Background: Isocyanates are the most frequent cause of occupational asthma in industrialized countries. Objective: We sought to investigate the utility of specific IgE measurement in the diagnosis of isocyanate-induced asthma. Methods: Fifty-eight of 101 patients referred for investigation were diagnosed as having isocyanate-induced occupational asthma by means of history, serial peak flow records, and bronchial provocation tests. Specific IgE antibodies to toluene diisocyanate:human serum albumin (HSA), diphenylmethane diisocyanate:HSA, and hexamethylene diisocyanate:HSA were measured in all patients by Phadebas RAST. Results: Twenty patients had a RAST ratio of 2 or greater to at least one isocyanate. Thirteen (28%) of the 46 patients with a positive provocation test response had a RAST ratio of 2 or greater, and nine (20%) had a RAST ratio of 3 or greater. Raising the RAST cut-off from 2 or greater to 3 or greater reduced its sensitivity but increased the specificity of the test to 100%. RAST measurement was most likely to be positive within 30 days of exposure. Serial measurements suggested that the half-life of the IgE antibodies was approximately 6 months. Evidence of cross-reactivity between isocyanate RAST responses was found in eight subjects. Conclusion: Specific IgE to isocyanates is a more specific than sensitive index of occupational asthma. With a RAST score of 3 or greater, it is wholly specific and therefore diagnostic of isocyanate-induced asthma. The sensitivity of specific IgE measurement is highest when blood is taken less than 30 days from last exposure, which is consistent with the observed half-life.(J Allergy Clin Immunol 1998;101:709-15.)
ISSN:0091-6749
1097-6825
DOI:10.1016/S0091-6749(98)70181-2