Are high- and low-molecular-weight sensitizing agents associated with different clinical phenotypes of occupational asthma?

BACKGROUND: High-molecular-weight (HMW) proteins and low-molecular-weight (LMW) chemicals can cause occupational asthma (OA) although few studies have thoroughly compared the clinical, physiological, and inflammatory patterns associated with these different types of agents. The aim of this study was to determine whether OA induced by HMW and LMW agents shows distinct phenotypic profiles. METHODS: Clinical and functional characteristics, and markers of airway inflammation were analyzed in an international, multicenter, retrospective cohort of subjects with OA ascertained by a positive inhalation challenge response to HMW (n = 544) and LMW (n = 635) agents. RESULTS: Multivariate logistic regression analysis showed significant associations between OA caused by HMW agents and work-related rhinitis (OR [95% CI]: 4.79 [3.28-7.12]), conjunctivitis (2.13 [1.52-2.98]), atopy (1.49 [1.09-2.05]), and early asthmatic reactions (2.86 [1.98-4.16]). By contrast, OA due to LMW agents was associated with chest tightness at work (2.22 [1.59-3.03]), daily sputum (1.69 [1.19-2.38]), and late asthmatic reactions (1.52 [1.09-2.08]). Furthermore, OA caused by HMW agents showed a higher risk of airflow limitation (1.76 [1.07-2.91]), whereas OA due to LMW agents exhibited a higher risk of severe exacerbations (1.32 [1.01-1.69]). There were no differences between the two types of agents in the baseline sputum inflammatory profiles, but OA caused by HMW agents showed higher baseline blood eosinophilia and a greater postchallenge increase in fractional nitric oxide. CONCLUSION: This large cohort study describes distinct phenotypic profiles in OA caused by HMW and LMW agents. There is a need to further explore differences in underlying pathophysiological pathways and outcome after environmental interventions.

Are allergen batch differences and the use of double skin prick test important?

BACKGROUND: Skin prick tests (SPT) are widely used both in clinical diagnostics and in research. The standardization of allergen extracts is well documented to be crucial for the validity of SPT, whereas less emphasis has been placed on reproducibility and the SPT procedure itself. The objectives of this study are to clarify how the double skin prick test procedure influence the sensitivity and specificity of the test and to analyse the differences in weal size in skin prick tests between two batches of allergen extracts from the same vendor. METHODS: The association between rhinitis and SPT was assessed among 1135 persons from a general population sample. SPT was performed twice with 10 common aeroallergens. In a subsample of 90 persons SPT was performed simultaneously with five of the allergens using different batches. RESULTS: Thirty percent had at least one positive SPT. Among asthmatics this number was 62%. Only minor differences were seen between the sizes of two weals from the same batch. A second SPT with the same batch did not change the association between rhinitis and sensitization. When performing SPT with two different batches disagreement was observed in 2% (Birch) to 11% (Cat) of the subjects. CONCLUSIONS: Performing SPT twice with the same allergen batch does not enhance the validity of the test, and value of double testing can be questioned. Considerable differences in SPT response with different batches from the same manufacturer were observed. Thus inter batch differences in allergen extracts might be a source of variability.

A systematic review of occupational exposure to coal dust and the risk of interstitial lung diseases.

Objective: Exposure to coal dust can cause interstitial lung disease (ILD), but whether this is due to pure coal or to the contents of quartz in coal is less clear. Here, we systematically reviewed the relation between 'pure coal' and ILD. Methods: In a systematic review based on PRISMA criteria 2945 articles were identified. Strict eligibility criteria, which evaluated the 'pure coal effect', led to the inclusion of only nine studies. Results: Among these nine studies six studies indicated an independent effect of the non-quartz part of coal on the development and progression of ILD, two did not demonstrate an effect and one was inconclusive. Conclusions: Although an independent effect of non-quartz coal dust on the development of ILD is supported, due to methodological limitations the evidence is limited and further evidence is needed.

[Allergology in Denmark 2006]. / Allergologi i Danmark 2006.

Allergic diseases are prominent, possibly life threatening, and a cause of worldwide concern. Evidence-based education of doctors in the specialty of allergology is a prerequisite for correct diagnosis and treatment of patients with allergic diseases. Recently, the specialty of allergology has been abolished in Denmark, without any upgrading of the education of doctors in related specialties. As a consequence, one could fear that allergy expertise will be disappearing. We propose collaboration among experts from related specialties with joint mediation of knowledge through a centre of allergology, common educational programs for doctors in training and physician specialists, and collaboration in regional centres of allergology.

[The significance of conditions when growing up on the prevalence of atopy in adult Danes]. / Opvaekstforholds betydning for atopiske lidelser hos voksne danskere.

INTRODUCTION: The prevalence of atopy in adults depends on both hereditary and environmental factors. The influence of environmental factors is explained in the "hygiene hypothesis" by maturational changes in the immunological system in response to limited microbiologic challenges in early life. Several studies have indicated protective effects of varying conditions in early life, e.g., living on a farm and in particular with livestock. This study analyses this problem in a Danish population. METHODS: This cross-sectional study used the European Community Respiratory Health Survey (ECRHS) protocol. A screening questionnaire concerning asthma, asthma-related symptoms and nasal allergy supplemented by questions about environmental factors was distributed to 10,000 randomly chosen individuals, 20 to 44 years of age, in five Danish counties. RESULTS: The questionnaire was answered by 7,271 individuals (72.7%). The prevalence of asthma and nasal allergy in adults was independent of growing up in the city or the country, but a significant inverse association was seen when growing up in the country in proximity to livestock. This effect remained after controlling for different hereditary and environmental factors. DISCUSSION: The results of this population-based study are consistent with the results from similar international studies. This study demonstrates that growing up in the country with contact with livestock protects against the development of asthma and nasal allergy in adults.