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

Abstract

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 sensi-tive 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 seasondependent upper and lower airway inflammatory response, resembling the continuous inflammation in HDM-sensitive children.

Outdoor pollen‐related changes in lung function and markers of airway inflammation: A systematic review and meta‐analysis

“…These are summarized in Table 1. Most studies were conducted in Europe, 23,24,36‐44,46,47,49,52‐55,57‐60 with some in North America 45,50,51,56 and one in Asia 48 …”

“…The sample sizes ranged from 14 to 2063, with a median of 55. Five studies 24,37,38,53,56 investigated children only (age range: 5–12), three 23,36,55 investigated children and adolescents (age range: 8–16), three 44,52,54 investigated adolescents and adults (age range: 12–58), and sixteen 39‐43,45‐51,57‐60 investigated adults only (age range: 17–68). In all studies, 'ever asthma' and 'ever SAR' were defined by having (i) a history of asthma or allergic rhinitis that was confined to the pollen season; plus (ii) a positive skin‐prick test (SPT) and/or radioallergosorbent test (RAST) to the pollen allergen in the study.…”

“…The main limitations and biases arose from limited power and/or lack of justification on sample sizes, 23,24,36‐60 lack of information on pollen data collection, 36 the use of a Rotorod sampler 56 (lower collection efficiency compared to Burkard 61 ), lack of information on outcome measurements 42 (measurement bias), lack of information on non‐respondents 36,37,40‐51,54,56‐60 (potential selection bias) and lack of adjustment for a priori key confounders such as temperature and humidity 24,36,37,39 (confounding bias). Some studies 42,43,45,47,53,54 did not state whether statistical methods were used for within‐group paired samples when it was appropriate to do so (appropriateness of statistical testing).…”

Experimental inhalation of fragrance allergens in predisposed subjects: effects on skin and airways

“…The level of FeNO and blood eosinophils can be considered as markers of, not necessarily allergic, inflammation. 35 While the absolute number of eosinophils remained unchanged, total leucocyte number increased, probably due to circadian variation. By contrast, the level of FeNO was even reduced immediately after exposure to ISO.…”

“…This was true for provocative doses as well as for dose–response slopes which did not require a 20% fall in FEV 1 . The level of FeNO and blood eosinophils can be considered as markers of, not necessarily allergic, inflammation 35 . While the absolute number of eosinophils remained unchanged, total leucocyte number increased, probably due to circadian variation.…”