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Cat allergen exposure in Swedish schools is high enough to maintain continuous bronchial hyperreactivity and to cause symptoms in children with asthma who are sensitized to cat
Linköping University, Department of Molecular and Clinical Medicine, Pediatrics. Linköping University, Faculty of Health Sciences.
Linköping University, Department of Molecular and Clinical Medicine, Allergy Centre. Linköping University, Faculty of Health Sciences.
Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Respiratory Medicine. Linköping University, Faculty of Health Sciences.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Background: Exposure to indoor allergens play a major role for development of sensitization and induction of allergic inflammation, bronchial hyperreactivity and symptoms in sensitized individual.

Objective: fu this study, we investigated the individual exposure levels of cat allergen, Fel d1, among asthmatic schoolchildren sensitized to cats. We studied the exposure relationship with symptoms, medication, lung functions, bronchial hyperreactivity (BHR) and mediators of allergic inflallrmation.

Methods: Ten school children with known allergy to cats were selected from 5 schools in Linköping, Sweden. All children had positive skin test to cats. We collected dust samples from homes and schools. All children carried a portable air-sampler in the schools during the period of 4-6 weeks. Air was also sampled fi·om the bedroom. The children performed lung function (PEF) twice daily using a digital Peak flow meter. They maintain symptom and medication chart once in a week. We performed methacholine bronchial provocation test (PD20) and analyzed mediators of allergic inflammation (s-ECP, EPX and MPO) iu blood and urine at the beginning and at the end of the study period. Dust and air samples were analyzed for major cat allergen (Fel d1) using ELISA.

Results: Exposure levels of cat allergen varied from 0,5 µg/g to 751 µg/g dust in homes (median, 36 µg/g) and from 17 µg/g to 378 µg/g in schools (median, 137 µg/g). Airborne allergen levels varied from 13 to 2184 pg/m3 (median, 43 pg/m3) in the homes and 68 to 7718 pg/m3 (median 352 pg/m3) in the schools. The mediators of allergic inflammation ranged from 4 to 57 µg/L for ECP, from 12 to 73 µg/L for EPX and from 148 to 581 µg/L for MPO. All children had bronchial hyperreactivity and all but one child used asthma/allergy medicine during the entire study period. A significant relationship (p<0.05) was found between the peak allergen exposure and symptoms, airborne allergens and BHR of the children.

Conclusions: Our study suggests, that school is an important source of cat allergen exposure, that cat sensitized asthmatic children inhale a substantial amount of cat allergen in the schools, that despite treatment of asthma including regular use of inhaled corticosteroids, 8 pg to 2336 pg of cat allergen inhaled per minute is sufficient enough to maintain a continuous airway hyper-responsiveness among this group of children.

National Category
Medical and Health Sciences
URN: urn:nbn:se:liu:diva-85007OAI: diva2:563529
Available from: 2012-10-30 Created: 2012-10-30 Last updated: 2012-10-30
In thesis
1. Pollinosis in children with special reference to the development of asthma
Open this publication in new window or tab >>Pollinosis in children with special reference to the development of asthma
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Children with rhinoconjunctivitis and increased bronchial hyperreactivity (BHR) are prone to develop asthma later in life. Eosinophil granule proteins in serum are indirect measures of eosinophil activity and regarded as markers of inflammation. Measurement of eosinophil cationic protein (ECP) has also been evaluated for prediction, diagnosis and monitoring of treatment in children with asthma. In 1992, a multicenter preventive allergy treatment study (PAT-study) was started in order to prevent the development of asthma in children with pollinosis using specific immunotherapy treatment (SIT). Sensitization to cat allergen is common in asthma and up to 50% of children with asthma are sensitized. Exposure to cat allergen can not be avoided because exposure occurs in schools and even in homes without a cat and is a major cause of persisting airway inflammation and asthma in cat sensitized schoolchildren. Data are needed to know the level of allergen maintaining BHR or asthma.

The aims of the thesis were: 1) To assess the relationship between seasonal symptoms of allergy, BHR, PEP-variability and release of markers of inflammation. 2) To investigate the level of markers of inflammation, and PEF variability, in healthy school children. 3) To investigate the diagnostic value of the tests e.g. BHR and mediators of allergic inflammation for diagnosis of asthma in pollinosis. 4) To investigate the efficacy of SIT regarding prevention of asthma, BHR, and polysensitization. 5) To assess, the levels of cat allergens inhaled daily by asthmatic schoolchildren sensitized to cat and relate the levels of allergen to symptoms of asthma and BHR.

The PAT study population comprised 205 birch and/or grass pollen allergic children with pollinosis, from 7 centres in 5 countries in Northern and Central Europe, 28 were enrolled in the Linköping. We recruited 56 healthy school children to study the normal level of inflammatory markers and PEFR variability and 10 asthmatic schoolchildren sensitized to cat to assess the allergen levels in their daily environment.

In the pollinosis children, sensitization status was determined by skin and conjunctival provocation test and RAST. Mediators of allergic inflammation like ECP, EPX, and neutrophil mediators like MPO were measured by RIA methods, non-specific BHR by Methacholine and/or cold air challenge tests and bronchial lability by PEF variability using Mini Wrights Peak-Flow meters. The level of cat allergens in dust samples were measured by ELISA, and in air by amplified ELISA methods. SIT was given by birch and/or grass pollen allergen extracts (Alutard), during a period of 3 years.

In pollinosis children in Linköping, there was no correlation between mediators of allergic inflammation in serum and symptoms and signs of clinical asthma. BHR and PEFR-variability persisted in the autumn, though s-ECP and s-EPX did not, indicating that mediators of inflammation do not reflect asthma. Positive MBPT and IHCA tests were more often found in the children with clinical asthma. The other investigated tests were not useful for screening of asthma in this group of children with pollinosis. In healthy schoolchildren, the mean daily PEF variations were 7.35 and 6.74%, and the 9Sth percentiles were 18 and 14% during the spring and autumn respectively. The 95th percentils for s-ECP were 41 and 38 µg/L, for s-EPX 74 and 62µg/L, for s-MPO 987 and 569 µg/L and for u-EPX tucreatinine 165 and 104 µg/mmol, during spring and autumn, respectively. Our findings for mediator levels in schoolchildren were higher than reported in adults. There was a significant decrease in the levels of the eosinophil and neutrophil mediators from May to November (p ≤ 0.001) and so did the PEF variability (p=0.037) in our healthy children. As normal reference values post seasonal data would be more appropriate. In the environment of cat sensitive children, exposure levels of cat allergen varied from 0.5 µg/g to 751 µg/g dust in homes (median, 36 µg/g) and from 17 µg/g to 378 µg/g in schools (median, 137 µg/g). Airborne allergen levels varied from 13 to 2184 pg/m3 (median, 43 pg/m3 ) in the homes and 68 to 7718 pg/m3 (median 352 pg/m3) in the schools. The inhaled dose was 8 pg to 2336 pg/min. A relation between BHR and exposure level was found. In the PAT-study, children actively treated with SIT had significantly fewer asthma symptoms after 3 years (odds ratio 2.52; p<0.05) and MBPT was improved (p<0.05) compare to the control group. Thus, SIT reduced the development of asthma in our children with pollinosis.

We followed the pollinosis children in Linköping in our centre for 11 years. Our findings were: I) there was a trend of diminishing in sensitivity to MBPT and in PEF variation with age. 2) Pollen counts in different years influenced MBPT results in that particular year. 3) MBPT in 1992 could predict the development of asthma in 1994.

Place, publisher, year, edition, pages
Edsbruk: Linköpings universitet, 2004. 95 p.
Linköping University Medical Dissertations, ISSN 0345-0082 ; 842
National Category
Medical and Health Sciences
urn:nbn:se:liu:diva-22415 (URN)1630 (Local ID)91-7373-809-3 (ISBN)1630 (Archive number)1630 (OAI)
Public defence
2004-11-30, Eken, Hälsouniversitetet, Linköping, 13:00 (Swedish)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2012-10-30Bibliographically approved

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