Increased eosinophil transmigration after nasal allergen challenge in children with allergic asthma and rhinitis.

BACKGROUND: Eotaxin and interleukin-5 together provide the signal essential for eosinophil transmigration to airway tissue in allergic reactions. However, it is not known whether peripheral blood eosinophils (PBE) possess an increased transmigration capacity in vitro after allergen challenge in vivo before they leave the circulation. We aimed to determine whether PBE in cat-sensitized children have increased spontaneous and/or eotaxin-induced transmigration capacity in vitro, and to what extent allergen challenge alters this feature. METHODS: Fourteen cat-allergic children and four healthy controls underwent nasal challenge with cat-allergen. Blood samples were drawn prechallenge and at 2 h and 24 h postchallenge. We analyzed the in vitro transmigration of PBE, with and without eotaxin as a chemoattractant. We used a transmigration assay with fibronectin-coated membranes. Eosinophil cationic protein (ECP) and PBE counts were run in parallel. RESULTS: The spontaneous transmigration capacity of eosinophils in vitro was significantly higher at 2 h after allergen challenge (P < 0.01 vs. prechallenge) and returned to prechallenge levels at 24 h postchallenge (P < 0.02 vs. 2 h postchallenge). Addition of eotaxin further augmented the increased transmigration. In concordance, no accompanying changes were measured in the levels of eosinophils in blood or ECP in serum. Furthermore no spontaneous or eotaxin-induced eosinophil transmigration was detected in healthy controls. CONCLUSION: PBE possess increased spontaneous (and eotaxin-induced) capacity to transmigrate as early as 2 h after allergen challenge in allergic children, without accompanying signs of eosinophil activation in terms of increased PBE count or ECP level. This is probably due to the increased stage of activation of the eosinophil, often referred to as "priming".

Down-regulated IL-5 receptor expression on peripheral blood eosinophils from budesonide-treated children with asthma.

BACKGROUND: The expression and function of cytokine receptors on peripheral blood eosinophils (PBE) from healthy and asthmatic children are poorly characterized. METHODS: The PBE count and expression of IL-5 receptor (R) and GM-CSFR positive PBE was analyzed in nonsteroid-treated asthmatic children (n = 13), budesonide-treated asthmatic children (n = 24) and healthy children (n = 16) by flow cytometry. Alterations in intracellular EG2-epitope expression were used to measure the in vitro responsiveness of PBE to recombinant IL-5 and GM-CSF. RESULTS: The PBE count was increased (P < 0.05) in both asthmatic groups, independent of treatment, as compared to healthy children. The IL-5R expression on PBE, as well as the in vitro responsiveness of PBE to recombinant IL-5, was reduced (P < 0.05), in budesonide-treated asthmatic children compared to nonsteroid-treated asthmatic children and healthy children. The proportion of GM-CSFR positive PBE and in vitro responsiveness of PBE to recombinant GM-CSF were not different between the groups. In vitro treatment with budesonide did not down-regulate the proportion of IL-5R positive PBE. CONCLUSIONS: Budesonide-treatment of asthmatic children induces a selectively reduced IL-5R expression on PBE, concomitant with a reduced in vitro responsiveness of PBE to IL-5. We suggest that this budesonide-related down-regulation of the IL-5R might be a mechanism by which steroid treatment inhibits the action of IL-5 on eosinophil accumulation and activation in vivo.

Eosinophil markers in blood, serum, and urine for monitoring the clinical course in childhood asthma: impact of budesonide treatment and withdrawal.

BACKGROUND: Markers of airway inflammation are needed for prediction of asthma deterioration and evaluation of disease severity. Few studies have focused on the dynamics of airway inflammation as reflected by the activity of the eosinophils and their proteins after withdrawal of inhaled corticosteroids. OBJECTIVE: Our goal was to investigate the effect of withdrawal of inhaled budesonide on eosinophil count in blood and eosinophil proteins in serum and urine and to relate the levels of these markers to the risk of symptoms of asthma, increased bronchial hyperresponsiveness, and deterioration of lung function. METHODS: Thirty-three children were randomly selected to continue or discontinue use of inhaled budesonide in a double-blind, placebo-controlled study. They were followed up for 4 months with regular analysis of blood, serum, and urine samples; lung function; and methacholine challenges. Eosinophil activity markers were analyzed. Age-matched healthy children provided reference data for all parameters measured. RESULTS: The eosinophil number in blood and eosinophil protein levels in serum (serum eosinophil cationic protein [ECP] and serum eosinophil peroxidase [EPO]) increased significantly in the withdrawal group, and the difference between the groups was significant (P =.02 for all). Twenty-nine percent of the children in the withdrawal group remained symptom free. This subgroup had eosinophil counts at baseline below 350/microL, a serum ECP level below 15 microg/L, and a serum EPO level below 25 microg/L, each of which was related to a low risk of exacerbation (relative risk = 0.37, 0.48, and 0.37 respectively; P <.05 for all). All eosinophil markers were lower in the healthy children than in the symptom-free children with asthma. CONCLUSION: Our data indicate that eosinophil count and/or ECP and EPO levels can be used to estimate the short-term risk of deterioration and the need for corticosteroid treatment in cases of mild and moderate allergic asthma.

Markers of inflammation and bronchial reactivity in children with asthma, exposed to animal dander in school dust.

Several studies have confirmed the presence of animal dander allergens in school dust but the effect of this indirect animal exposure on health has not been evaluated. In this study we investigated bronchial reactivity and markers of eosinophil activity and inflammation during two separate weeks of school in 10 children with mild asthma and a positive skin prick test to cat and dog. At the beginning and the end of the first week the children underwent bronchial challenges with methacholine, and at the beginning and the end of the second week they underwent nasal lavages (NAL) and induced sputum samplings. Blood and urine samples for analysis of inflammatory markers were obtained before and after both school weeks. Peak expiratory flow (PEF) and symptoms of asthma and allergy were recorded daily, and spirometry was performed on each visit. The exposure to animal dander allergens was estimated from dust samples obtained in the subjects' schools and homes. Bronchial sensitivity to methacholine increased in the week when this was measured. The proportion of eosinophils in peripheral blood, and urinary eosinophil protein X (EPX), decreased in both weeks. There was a trend towards an increase of eosinophil peroxidase (EPO) and myeloperoxidase (MPO) in sputum in the week when these proteins were measured. The concentrations of cat (Fel d1) and dog (Can f1) allergens were higher in dust collected in schools than in homes. Our results show that in children with mild asthma and animal dander allergy, there is a significantly increased bronchial sensitivity to methacholine after one school week. There is also a significant decrease in the number of circulating eosinophils and a trend towards an increase of sputum EPO, which could correlate with the early phase of eosinophil recruitment to the lungs. These effects may be related to the continuous exposure to animal allergens in school dust.