Perfetti L, Hébert J, Lapalme Y, Ghezzo H, Gautrin D, Malo J L
Department of Chest Medicine, Sacré-Coeur Hospital, Montreal, Québec, Canada.
Clin Exp Allergy. 1998 Jan;28(1):66-73. doi: 10.1046/j.1365-2222.1998.00193.x.
One possibility, among others, for explaining the persistence of asthma symptoms in occupational asthma (OA) after the cessation of exposure to the causal agents may be that subjects become sensitized to ubiquitous inhalants.
The aim of this study was to evaluate the development or increase of IgE-mediated sensitization to ubiquitous allergens, both to high- and low-molecular-weight agents, in 100 subjects with OA after cessation of exposure.
Subjects were evaluated on a first visit, at the time of diagnosis of OA, coinciding with the cessation or diminution of exposure to the causal agent, and on a second visit, 5.8+/-3.3 years afterwards. At each visit, a history of ocular, nasal and asthmatic symptoms related to exposure to common allergens was obtained together with spirometry and assessment of bronchial responsiveness to methacholine. We analysed total IgE and specific IgE to Dermatophagoides farinae, D. pteronyssinus, birch, ragweed and timothy grass pollens, cat and dog danders, and Alternaria, using enzyme allergosorbent test (EAST) from blood samples taken on each visit.
Total IgE levels showed a tendency to diminish. No changes were found in the number of positive EAST (presence of detectable levels of specific IgE) or in the levels of specific IgE. Although significantly more symptoms of rhinoconjunctivitis and asthma in contact with house dust (P < 0.05) and pets (P < 0.01) were reported on the second visit than on the first, no significant changes in the frequency of symptomatic sensitized subjects were found.
Subjects with OA are unlikely to develop IgE-dependent sensitization to common inhalants after removal from exposure to occupational agents.
在职业性哮喘（OA）患者中，接触致病因子停止后哮喘症状仍持续存在，其可能的原因之一是患者对普遍存在的吸入性物质产生了致敏。
本研究旨在评估100例职业性哮喘患者在停止接触致病因子后，对普遍存在的过敏原（包括高分子量和低分子量物质）的IgE介导的致敏反应的发展或增加情况。
在首次就诊时（即诊断为职业性哮喘时，此时接触致病因子已停止或减少）以及5.8±3.3年后的第二次就诊时对患者进行评估。每次就诊时，均获取与接触常见过敏原相关的眼、鼻及哮喘症状病史，同时进行肺功能测定及支气管对乙酰甲胆碱反应性评估。我们使用酶联免疫吸附试验（EAST）分析每次就诊时采集的血样中的总IgE以及针对粉尘螨、屋尘螨、桦树、豚草和梯牧草花粉、猫和狗皮屑以及链格孢属的特异性IgE。
总IgE水平呈下降趋势。EAST阳性数量（可检测到特异性IgE水平）或特异性IgE水平均未发现变化。尽管第二次就诊时报告的与屋尘（P<0.05）和宠物（P<0.01）接触相关的鼻结膜炎和哮喘症状明显多于第一次就诊时，但有症状的致敏患者频率未发现显著变化。
职业性哮喘患者在脱离职业性致病因子接触后，不太可能对常见吸入性物质产生IgE依赖性致敏。
