The prevalence of allergic sensitisation in immigrant children in The Netherlands.

BACKGROUND: Differences in the prevalence of allergic sensitisation have been reported in immigrant children living in the same urban environment. The purpose of this study is to investigate the prevalence of allergic sensitisation in school children of Dutch, Turkish and Moroccan origin. METHODS: The prevalence of sensitisation to aero-allergens was assessed using the skin prick test in a non-selected sample of 512 children (response rate 54%) living in the same inner city district of Utrecht. In addition, exhaled nitric oxide (FeNO) was determined. RESULTS: The prevalence of allergic sensitisation was dependent on the ethnic origin. As compared with Dutch children (19.1%), a higher prevalence of allergic sensitisation was observed in immigrant children for whom both parents were born in Turkey (23.6%, not significant) or Morocco (30.6%, p<0.05). The prevalence of allergic sensitisation in Dutch children was nearly 2 times lower than the reported prevalence in German children. In all sensitised children, the mean FeNO value was significantly (p<0.05) higher than in non-sensitised children, and the mean FeNO level was highest in Moroccan children sensitised to indoor allergens. CONCLUSION: In The Netherlands, immigrant children show a higher prevalence of allergic sensitisation as compared to Dutch children.

Acute effect of air pollution on respiratory complaints, exhaled NO and biomarkers in nasal lavages of allergic children during the pollen season.

During 2 months of the pollen season, the acute and putative adjuvant effect of traffic-related air pollution on respiratory health was investigated in children sensitised to grass pollen or house dust mite (HDM). Respiratory complaints were objectified via measurement of exhaled NO and inflammatory mediators in nasal lavage (NAL). During the study children, skin prick negative (n = 31) or positive to grass pollen (n = 22), HDM (n = 34) or grass pollen + HDM (n = 32), kept a daily diary on respiratory symptoms, and NAL and exhaled air was sampled twice a week. The level of air pollutants and pollen was monitored continuously. Like children sensitised to HDM, those sensitised to pollen reported respiratory complaints (shortness of breath, itchy eyes or blocked nose) more frequently than non-sensitised children during (but not before) the pollen season; the respiratory complaints of sensitised children were independent of the pollen level. In addition, exposure to increased levels of PM(10) induces 'shortness of breath' in pollen- and HDM-sensitised children, whereas ozone induces a blocked nose in HDM-sensitised children. Combined exposure to PM(10) + pollen and O(3) + pollen induces a blocked nose in both HDM-sensitised children and children sensitised to pollen + HDM. Significant positive associations were found between eNO and the levels of NO(2), CO, PM(2.5) and pollen in both sensitised and non-sensitised children. At the start of the pollen season, the NAL concentration of eosinophils and ECP in pollen-sensitised children was increased compared to winter, but their levels were not further affected by increased exposure to pollen or air pollution. In conclusion, during the pollen season, sensitised children continuously report a high prevalence of respiratory complaints which coincides with increased levels of upper and lower airway inflammatory markers. No additional pro-inflammatory effect of air pollution was observed, which indicates that air pollution does not facilitate allergen-induced inflammatory responses.

Exhaled NO level and number of eosinophils in nasal lavage as markers of pollen-induced upper and lower airway inflammation in children sensitive to grass pollen.

OBJECTIVES: This study investigates the upper and lower inflammatory response induced by natural exposure to grass pollen in atopic and non-atopic children. METHODS: After children's atopic profile had been assessed, their nasal lavage fluid (NAL) and exhaled air was sampled once before and once during the pollen season. Level of nitric oxide (NO) was determined in exhaled air, and the following mediators were measured in NAL: ECP, IL-6, IL-8, albumin, uric acid, and urea. The number of eosinophils in NAL was determined after Giemsa staining. During the experiment ozone and pollen levels were measured continuously. RESULTS: During the pollen season the level of grass pollen was 95 pollen grains per cubic metre. At baseline, 8.0% and 5.4% of total cells in NAL of children sensitive to, respectively, house dust mite (HDM) and pollen + HDM were eosinophils, whereas virtually no eosinophils were observed in NAL of non-atopic children. In contrast to the non-atopic and HDM groups, in children sensitive only to grass pollen, grass pollen induced a threefold increase in the percentage of NAL eosinophils and a 2.5-fold increase in the NAL level of ECP ( P<0.05). In all groups, the NAL levels of albumin, uric acid, urea, IL-6 and IL-8 were not significantly increased by pollen exposure. At baseline, children sensitive to HDM showed significantly higher exhaled nitric oxide (eNO) values than non-atopic subjects and children sensitive only to pollen (79 to 141% increase). During pollen exposure eNO of children sensitive only to pollen increased from 35.8 to 64.5 ppb ( P<0.05), whereas no increase in eNO was observed in the other children. CONCLUSION: Pollen-sensitive children show a season-dependent upper and lower airway inflammatory response, resembling the continuous inflammation in HDM-sensitive children.