Tee R D, Cullinan P, Welch J, Burge P S, Newman-Taylor A J
Department of Occupational and Environmental Medicine, Imperial College School of Medicine (National Heart and Lung Institute), London, United Kingdom.
J Allergy Clin Immunol. 1998 May;101(5):709-15. doi: 10.1016/S0091-6749(98)70181-2.
Isocyanates are the most frequent cause of occupational asthma in industrialized countries.
We sought to investigate the utility of specific IgE measurement in the diagnosis of isocyanate-induced asthma.
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.
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.
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.
在工业化国家，异氰酸酯是职业性哮喘最常见的病因。
我们试图研究特异性IgE检测在异氰酸酯诱发哮喘诊断中的作用。
101例接受检查的患者中，58例根据病史、连续峰流速记录和支气管激发试验被诊断为异氰酸酯诱发的职业性哮喘。采用Phadebas RAST法检测所有患者针对甲苯二异氰酸酯：人血清白蛋白（HSA）、二苯基甲烷二异氰酸酯：HSA和六亚甲基二异氰酸酯：HSA的特异性IgE抗体。
20例患者针对至少一种异氰酸酯的RAST比值为2或更高。46例激发试验反应阳性的患者中，13例（28%）的RAST比值为2或更高，9例（20%）的RAST比值为3或更高。将RAST临界值从2或更高提高到3或更高会降低其敏感性，但会将检测的特异性提高到100%。RAST检测在接触后30天内最有可能呈阳性。连续检测表明，IgE抗体的半衰期约为6个月。在8名受试者中发现了异氰酸酯RAST反应之间的交叉反应证据。
异氰酸酯特异性IgE是职业性哮喘的一个特异性高于敏感性的指标。RAST评分3或更高时，它具有完全特异性，因此可诊断异氰酸酯诱发的哮喘。特异性IgE检测的敏感性在末次接触后不到30天采血时最高，这与观察到的半衰期一致。
