Short Report |
Challenge testing in the diagnosis of occupational allergic conjunctivitis
1 Department of Occupational Medicine, Nofer Institute of Occupational Medicine, Lodz, Poland
2 Centre of Occupational and Environmental Allergy, Nofer Institute of Occupational Medicine, Lodz, Poland
3 Outpatient Clinic of Occupational Diseases, Nofer Institute of Occupational Medicine, Lodz, Poland
4 Department of Environmental Diseases, Medical University, Lodz, Poland
Correspondence to: Tomasz Wittczak, Department of Occupational Medicine, Centre of Occupational and Environmental Allergy, Nofer Institute of Occupational Medicine, 8 Teresy Street, Lodz 91-348, Poland. Tel: +48 (42) 6314775; fax: +48 (42) 6314764; e-mail: tomekwit{at}imp.lodz.pl
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Abstract |
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Background Providing evidence for the allergic aetiology of ocular symptoms developing as a result of occupational exposure is important for compensation procedures in many countries.
Aim To perform cellular analysis of tear fluid before and after a specific challenge test with high-molecular weight allergens in symptomatic subjects.
Methods The subjects were 23 bakers with a history of conjunctivitis or rhinoconjunctivitis associated with occupational exposure to wheat flour and positive skin prick test with this allergen. A specific inhalation challenge test with wheat flour and a placebo test were performed. The symptom score (SS) and cellular changes in tear fluid and nasal washings were assessed.
Results Specific provocation test induced significant eosinophil influx in tear fluid in only six patients. No changes in the proportion of other cells could be observed. Cytological changes in tear fluid did not correlate with either ocular SS (Pearson r = 0.18, P = 0.40) or changes in the nasal lavage fluid or SS (Pearson r = 0.13, P = 0.56). However, an analysis of SS results obtained at 30 min and at 24 h after the challenge revealed that cellular changes in tear fluid correlated significantly both with the early and late changes in SS (Pearson r = 0.52, P < 0.05 and Pearson r = 0.81, P < 0.001, respectively).
Conclusions Analysis of cellular changes in tear fluid during specific inhalation challenge test seems to be a valuable diagnostic tool in occupational ocular allergy. However, the discrepancy between the findings of cellular analysis and SS revealed by the present study requires further research.
Keywords Allergen challenge; eosinophils; occupational allergic conjunctivitis; tears
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Introduction |
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Seeking evidence for the occupational origin of allergic ocular disorders is important for medical certification and compensation procedures. The present study was undertaken as a preliminary investigation as part of a larger project to search for an objective method of diagnosing occupational allergic conjunctivitis. Symptomatic subjects had cellular analysis of tear fluid performed before and after a specific challenge test with high-molecular weight allergens [1] and the diagnostic value of the method was assessed.
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Methods |
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The study group comprised 23 bakers with a history of work-related ocular symptoms induced by wheat flour and positive skin prick tests (SPTs). Seventeen of these patients also had occupational rhinitis due to flour allergens. None of the examined subjects was apparently symptomatic, but they were subject to occupational exposure to flour at the time of the study. The study was approved by the local Biomedical Ethics Committee and all the subjects submitted their written informed consent prior to the study.
The ophthalmic physical examination (using LSM-12000 High-Magnification Slit-Lamp Biomicroscope, Bio-Optics) was performed 10 min before and 1, 6 and 24 h after the specific challenge test with wheat flour.
SPT with a standard battery of common allergens and wheat flour was performed using a standardized technique [2].
The provocation test with wheat flour was performed in a worksite simulation setting (room space 6 m2, temperature 22–25°C) with the patient's own samples of the allergen and involved the patient sifting 
100 g of wheat flour for 30 min. A placebo test with potato flour was carried out 7 days before allergen provocation, using the same method to generate flour dust. The total dust concentration during the challenge was estimated to be 3.6 ± 6.3 mg/m3 (dust monitor GRIMM 1.105).
The symptom score (SS) of nasal and ocular symptoms was assessed 10 min before and 1, 6 and 24 h after the challenge. The number of sneezes and the degree of mucosal oedema, rhinorrhoea and itching were evaluated. Eye symptoms were assessed according to the scale developed by Abelson [3,4].
The scores for nasal and ocular symptoms were considered positive at values 
3 points.
An analysis of the cellular composition of nasal washings, as in the ‘nasal pool’ method, was performed 10 min before the provocation and 1, 6 and 24 h afterwards [5,6].
Tear fluid (50–100 µl) was collected with a standard glass capillary at the same time points after each challenge. The material was dried and stained using the May–Grunwald–Giemsa method.
At least a double increase in the percentage of eosinophils in the nasal washings and tear fluid with proportion of at least 5% after the provocation was considered significant.
For statistical analysis, Pearson's correlation coefficient was calculated (at P < 0.05) using Statistics 4.5 for Windows.
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Results |
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After the placebo test, none of the subjects presented eye symptoms or rhinitis (nasal and ocular SS < 3 points). The challenge with wheat flour simulating workplace conditions induced eye symptoms in 21 of 23 subjects, with mean SS amounting to 5.4 ± 0.9 points. In 13 patients, these symptoms occurred immediately after the provocation and lasted for 6 h (SS 6.1 ± 1.1 points). In eight patients, the symptoms developed 1 h after the provocation (SS 5.1 ± 1.3 points) and persisted 24 h after the provocation (SS 3.6 ± 1.8 points).
Seventeen subjects also reported symptoms of rhinitis during the allergen challenge, with mean SS amounting to 6.3 ± 1.5 points. In all patients from this group, the nasal symptoms occurred within 10–30 min after the provocation and lasted for at least 6 h (SS 5.9 ± 1.1 points).
In two subjects, the allergen challenge did not produce any clinical symptoms and in four subjects, only the eye symptoms, with no concomitant nasal symptoms.
The placebo test did not reveal any significant changes in the cellular content of the nasal lavage fluid (NLF) or in eosinophil proportion in tear fluid.
Flour allergen provocation produced a significant increase in the number and percentage of eosinophils in NLF obtained from the 17 patients with allergic rhinitis. In all of these patients, typical eye symptoms were also observed. The mean percentage of eosinophils amounted to 1.1% (±2.1%) before provocation, and 2.7% (±1.7%), 6.3% (±3.1%) and 4.2% (±2.4%) at, respectively, 1, 6 and 24 h after the provocation.
In six patients, the specific provocation test induced significant eosinophil influx in tear fluid. No changes in the proportion of other cells in tears could be observed. The clinical symptoms of allergic conjunctivitis (Table 1) also developed in these subjects. Moreover, five patients with significant cellular changes in tear fluid presented symptoms of rhinitis and significant cellular changes in NLF (Table 2). One patient did not develop any symptoms of rhinitis or NLF changes after allergen challenge and only isolated allergic conjunctivitis was recognized.
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The provocation test with wheat flour under the same conditions was also performed in seven healthy individuals with no ocular symptoms (control group). The results did not reveal any symptoms or cell influx in tear fluid in this group.
Cytological changes in tear fluid did not correlate either with ocular SS (Pearson r = 0.18, P = 0.40) or with NLF changes or SS (Pearson r = 0.13, P = 0.56). On the contrary, NLF changes were always accompanied by positive nasal SS results (Pearson r = 1.0). Significant correlation was observed also between ocular and nasal SS, as well as between ocular SS and NLF changes (Pearson r = 0.52, P < 0.05). However, when SS results obtained at 30 min and 24 h after the provocation were analysed separately, the cellular changes in tear fluid correlated significantly both with the early and late SS changes (Pearson r = 0.52, P < 0.05 and Pearson r = 0.81, P < 0.001, respectively).
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Discussion |
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After the specific provocation test, we observed eosinophil influx to tear fluid in only six patients. The reason for the lack of cellular changes remains unclear. One of the possible explanations may be an inadequate quantity of the tear fluid examined. Therefore, it was impossible to centrifuge that material to obtain cell sediment. The tear fluid had to be prepared (dried and stained) as a smear. The total number of visible cells was very low and the calculations of cell proportion may be inaccurate.
The discrepancy between the findings of cellular analysis and SS assessment requires further studies on larger populations exposed to different allergens. Such studies should include inhalatory and conjunctival provocation tests with the same allergens. The findings of the present study indicate that the SS after the provocation test should be interpreted with caution [7–9].
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Conflicts of interest |
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None declared.
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References |
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[Abstract/Free Full Text] - Abelson MB, George MA, Garofalo C. Differential diagnose of ocular allergic disorders. Ann Allergy (1993) 70:95–109.[Web of Science][Medline]
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- Friedlaender MH. Objective measurement of allergic reactions in the eye. Curr Opin Allergy Clin Immunol (2004) 4:447–453.[CrossRef][Medline]
- Bacon AS, Ahuluwalia P, Irani AM, et al. Tear and conjunctival changes during the allergen-induced early-and late-phase responses. J Allergy Clin Immunol (2000) 106:948–954.[CrossRef][Web of Science][Medline]
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