Efficacy and safety of low-dose sesame oral immunotherapy in paediatric patients: a protocol for a single-centre, randomised controlled trial.

INTRODUCTION: Sesame allergy, though with low prevalence, can result in severe, potentially life-threatening reactions and poses challenges in allergen avoidance due to hidden sources. In the majority of patients, sesame allergy persists and there is currently no effective long-term treatment available. Therefore, oral immunotherapy (OIT) is a promising alternative approach to managing sesame allergy. In this study protocol, we present a randomised controlled trial evaluating the efficacy and safety of OIT with low-dose sesame protein in paediatric patients. The study's aim is to compare OIT with a 300 mg maintenance dose of sesame protein against controls. METHODS AND ANALYSIS: 39 participants aged 3-17 with IgE-mediated sesame allergy confirmed by oral food challenge will be enrolled into the study. The trial will be conducted at the Paediatric Hospital of the Medical University of Warsaw, Poland. The study comprises two arms-sesame OIT and control. In the sesame OIT group, interventions will be administered once daily for up to 18 months. During the first phase, the dose will be escalated every 2-4 weeks, and in the second phase, the maintenance dose of 300 mg sesame protein will continue for 3 months. Members of the control group will receive standard treatment, which includes an elimination diet and will remain under observation for 1 year. The primary outcome is the proportion of participants tolerating a single dose of 4000 mg of sesame protein during the final oral food challenge in the experimental group versus the control group. Secondary outcomes assess adverse events, changes in immunological parameters and the maximum tolerated doses of sesame protein in each group. ETHICS AND DISSEMINATION: This study has been approved by the Ethics Committee of the Medical University of Warsaw (approval number: KB/269/2023). Results will be published in peer-reviewed journals and disseminated via presentations at international conferences. TRIAL REGISTRATION NUMBER: NCT06261554.

Is Component-Specific Antibody Testing Sufficient to Replace the Oral Food Challenge in the Diagnostics of Peanut-Sensitized Children? A Proof-of-Concept Study.

(1) Peanut allergy is associated with high risk of anaphylaxis which could be prevented by oral immunotherapy. Patients eligible for immunotherapy are selected on the basis of a food challenge, although currently the assessment of antibodies against main peanut molecules (Ara h 1, 2, 3 and 6) is thought to be another option. (2) The current study assessed the relationship between the mentioned antibodies, challenge outcomes, skin tests and some other parameters in peanut-sensitized children. It involved 74 children, divided into two groups, based on their response to a food challenge. (3) Both groups differed in results of skin tests, levels of component-specific antibodies and peanut exposure history. The antibody levels were then used to calculate thresholds for prediction of challenge results or symptom severity. While the antibody-based challenge prediction revealed statistical significance, it failed in cases of severe symptoms. Furthermore, no significant correlation was observed between antibody levels, symptom-eliciting doses and the risk of severe anaphylaxis. Although in some patients it could result from interference with IgG4, the latter would not be a universal explanation of this phenomenon. (4) Despite some limitations, antibody-based screening may be an alternative to the food challenge, although its clinical relevance still requires further studies.

Peanut contamination in food products: a real danger for allergic people?

Introduction: Allergy to peanut affects approximately 2% of children and in most cases persists throughout adult life. Seventeen peanut allergens have been identified so far and registered as "Ara h" molecules. Two of them, Ara h 1 and Ara h 3, are the most abundant proteins in the peanut extract. Since strict avoidance of peanut-containing food is the easiest way to prevent severe allergic reactions, manufacturers must label such products. However, consumers can still inadvertently be exposed to peanut allergens when foods become contaminated from processing lines shared with peanut products. Aim: To investigate whether food products with the label "may contain traces of peanuts", available on the Polish market, are actually contaminated with Ara h 1 and Ara h 3. Material and methods: Thirty food products with the label "may contain traces of peanuts", were purchased in Polish stores. Samples of the foods were analyzed by using Ara h 1/Ara h 3 ELISA kits. Results: Nearly one third of tested food products contained clinically relevant amounts of Ara h 1 and Ara h 3. The doses of both peanut allergens, when adjusted to the serving size of tested products, exceeded several times the eliciting dose 05 (the amount of the allergen, which is predicted to provoke a reaction in 5% of at-the-risk allergic population). Conclusions: Consumption of foods labelled as "may contain traces of peanuts" poses a significant risk for people allergic to peanuts. Physicians should advise their patients with peanut allergy to strictly avoid such products.

Sensitization to nut allergens in children with food allergy and other atopic diseases - just a coexistence?

Introduction: Allergy to nuts, the most common food allergy in childhood, is considered as a significant health problem. Aim: To investigate sensitization to selected nuts in children with or without atopic allergy. Material and methods: Retrospective analysis involved records of 598 children, diagnosed with food allergy. Laboratory data concerned screening for sensitization to major allergens of hazelnut, peanut and walnut. Results: Approximately 77.8% of children with food allergy presented at least one concomitant atopic disease: allergic rhinitis (52.9%), atopic dermatitis (48%) or asthma (31.4%). Nearly one-third experienced at least one episode of anaphylaxis. The nut-specific antibodies were found in 67% of children. Among them, 56% were sensitized to hazelnut, and 54% to peanut. Sensitization to other nuts was less frequent (< 30%). Only 27% of patients were mono-sensitized, the remaining 73% were co-sensitized to two or three of tested nuts. Noteworthy, the occurrence of sensitization varied among age-related groups, and also depended on clinical diagnosis. In patients with sole food allergy the frequency of sensitization was highest in youngest children, whereas, when accompanied by other atopic disease, it was highest in schoolchildren. In children without food allergy, but with another atopic disease, the prevalence of sensitization was relatively low, without any specific pattern. Conclusions: The analysis of sensitization patterns may help to identify patients with an increased risk, and gives the opportunity to introduce more effective prophylaxis. However, since even the first exposure to nuts may be sufficient to trigger the anaphylaxis, this risk should be considered as a serious issue at any age.

Prevalence of nut allergen sensitization among children in central Poland.

Introduction: The diagnostics of plant-derived food allergy may be challenging. However, the recognition of sensitization patterns in defined populations, especially in children, is clinically relevant as it enables the use of secondary prophylaxis to prevent life-threatening complications. Aim: To investigate the rates and sensitization patterns to nut allergens in children from central Poland. Material and methods: The retrospective assessment concerned data of 598 children diagnosed in a single centre due to suspected food allergy. The analysis included the results of component-based multiparametric assay Allergy Explorer2 (ALEX2). Results: The sensitization to particular nut allergens varied among patients, depending on their age and nut type. The sensitization to any nut was found in 67% of children, whereas sensitization to hazelnut and peanut was the most common (56% and 55% of all children, respectively). Hazelnut sensitization was predominant in every age, and its prevalence increased with age, while peanut sensitization was detected in more than half of individuals from all groups, except for teenagers (44% of cases). Among hazelnut molecules sensitization to Cor a 1.04 was the most prevalent (74% of sensitized children), and for peanut allergens - Ara h 1 (65% of sensitized patients). The simultaneous sensitization to hazelnut, peanut and walnut (two or all of them) was found in almost half of the entire group. Conclusions: Component-based diagnostics enables differentiation between primary and cross-reactive sensitization to nut allergens and detects co-sensitization. The clinical relevance of the latter observation is remarkable as co-sensitization increases the risk of life-threatening reactions even in trace nut contamination.

Exhaled breath condensates from healthy children induce cell death of in vitro cultured cells by activation of apoptosis.

INTRODUCTION: Exhaled breath condensate (EBC) is a liquefied air, containing a mixture of non-volatile compounds, reflecting pathophysiological status of the bronchopulmonary system. Therefore, EBC analysis may be useful in diagnostics and monitoring of various respiratory diseases. In previous studies it was found that EBC from asthmatic children contained several regulators of angiogenesis. In vitro experiments with EBCs from children with asthma revealed their weak influence on proliferation of various cells. Surprisingly, EBCs from healthy children led to apoptosis of all tested cells. AIM: To assess the expression of selected apoptosis-related proteins in human and murine cells exposed to EBC from healthy children. MATERIAL AND METHODS: EBCs from healthy children were added to cultures of murine endothelial cells (C166) or human lung fibroblasts (HLF) to induce their apoptosis. For proteome analysis the apoptosis pathway-specific protein microarrays were used. RESULTS: The homogenates from EBC-treated C166 cells contained low amounts of Hsp27, which correlated with their fast death. Contrary to C166, the lysates from EBC-treated fibroblasts displayed increased amounts of Hsp27, which correlated with delayed HLF response to the induction of apoptosis. Except for increased caspase-3 in EBC-treated HLF, none of the other apoptosis regulators revealed any significant changes in that analysis. CONCLUSIONS: The screening of apoptosis pathways with microarray technology allowed identification of two molecules, Hsp27 and caspase-3, involved in cellular response to EBC. However, the factor responsible for induction of the cytotoxic effect of EBC from healthy children still remains unknown.

DPP4 Inhibitors and COVID-19-Holy Grail or Another Dead End?

A novel coronavirus disease, COVID-19, has emerged as a global public health issue. Clinical course of disease significantly correlates with the occurrence of some comorbidities, among them type 2 diabetes. According to recent structural studies the dipeptidyl peptidase 4, a key molecule in the pathophysiology of diabetes, may influence the course of COVID-19. Since DPP4 inhibitors, gliptins, are widely used in diabetes patients, the exact role of DPP4 modulation in SARS-CoV-2 infection, at least in that group, urgently needs to be clarified. In this short review, we discuss this issue with more detail.

Is the composition of exhaled breath condensate a key to explain the course of COVID-19 in children?

INTRODUCTION: The relative resistance of children to severe course of the novel coronavirus infection remains unclear. We hypothesized that there might be a link between this phenomenon and observation from our previous studies concerning an inhibitory or cytotoxic effect of exhaled breath condensate (EBC) on endothelial cell cultures in children. AIM: Since we could not find any data on the similar effect caused by EBC in adults, the aim of our study was to evaluate and compare the biological activity of EBC in adults and children in an experimental in vitro model. Furthermore, in order to identify a putative agent responsible for these properties of EBC in children, we attempted to analyse the composition of selected EBC samples. MATERIAL AND METHODS: The influence of EBC samples on metabolic activity of endothelial cell line C-166 was assessed using colorimetric tetrazolium salt reduction assay (MTT assay). Selected EBC samples were fractionated using size exclusion chromatography and subjected to mass spectrometry analysis. RESULTS: Exhaled breath condensates in healthy children, but not in adults, revealed a cytotoxic effect on in vitro cell cultures. This effect was most significant in condensate fraction, which contained a prominent 4.8 kDa peak in the mass spectra. CONCLUSIONS: Breath condensates of healthy children contain the factor which reveals the inhibitory/cytotoxic effect on endothelial cell cultures. Although the physiological role of this agent remains unclear, its identification may potentially be useful in ongoing research on SARS-CoV-2/COVID-19.

Interstitial Lung Disease in Children With Selected Primary Immunodeficiency Disorders-A Multicenter Observational Study.

Primary immunodeficiencies (PIDs) are rare disorders of the immune system encompassing inborn errors of immunity. Primary antibody deficiencies constitute the largest group of PID with common variable immunodeficiency (CVID) being the most common symptomatic form. Combined immunodeficiencies (CID) accompanied by antibody deficiency can mimic CVID and these patients need the verification of the final diagnosis. Respiratory involvement, especially interstitial lung disease (ILD), poses a relevant cause of morbidity and mortality among patients with PID and in some cases is the first manifestation of immunodeficiency. In this study we present a retrospective analysis of a group of children with primary immunodeficiency and ILD - the clinical, radiological, histological characteristics, treatment strategies and outcomes. Eleven children with PID-related ILD were described. The majority of them presented CVID, in three patients CID was recognized. All patients underwent detailed pulmonary diagnostics. In eight of them histological analysis of lung biopsy was performed. We noted that in two out of 11 patients acute onset of ILD with respiratory failure was the first manifestation of the disease and preceded PID diagnosis. The most common histopathological diagnosis was GLILD. Among the analyzed patients three did not require any immunosuppressive therapy. All eight treated children received corticosteroids as initial treatment, but in some of them second-line therapy was introduced. The relevant side effects in some patients were observed. The study demonstrated that the response to corticosteroids is usually prompt. However, the resolution of pulmonary changes may be incomplete and second-line treatment may be necessary.

Influence of exhaled breath condensates from children with asthma on endothelial cells cultured in vitro. Do we really know everything about our breath condensate?

INTRODUCTION: Asthma-associated remodelling involves subepithelial fibrosis and increased vascularization of the bronchial wall. The latter may be associated with excessive production of several angiogenesis regulators which may be found in exhaled breath condensates (EBCs) collected from children with asthma. AIM: To assess the influence of EBC samples of asthmatic children and healthy controls on in vitro cultures of normal human lung microvascular endothelial cells (HLMVEC) and murine endothelial cell line (C-166). Moreover, the proteomic profile of cytokines in EBC samples was analysed. MATERIAL AND METHODS: Breath condensates collected from children with mild asthma (n = 10) and from healthy controls (n = 10) were used for experiments. Colorimetric tetrazolium salt reduction assay was used to evaluate the effect of EBCs on HLMVEC and C-166 cell lines. Furthermore, influence of EBCs on C-166 cell line was assessed using Annexin V-binding assay. The cytokine screening of EBC samples was performed using a proteome microarray system. RESULTS: The EBCs from patients with asthma revealed a weak inhibitory influence on human and murine endothelial cells. Surprisingly, EBCs from healthy children led to cell death, mainly by the induction of apoptosis. There were no statistically significant differences in the cytokine profile between EBC samples from children with asthma and healthy controls. CONCLUSIONS: Our preliminary report shows for the first time that the incubation of EBCs from healthy controls induced apoptosis in endothelial cells. The detailed mechanism responsible for this action remains unknown and requires further research.

Truncating mutations in exons 20 and 21 of OFD1 can cause primary ciliary dyskinesia without associated syndromic symptoms.

BACKGROUND: Primary ciliary dyskinesia (PCD) is a motile ciliopathy, whose symptoms include airway infections, male infertility and situs inversus. Apart from the typical forms of PCD, rare syndromic PCD forms exist. Mutations of the X-linked OFD1 gene cause several syndromic ciliopathies, including oral-facial-digital syndrome type 1, Joubert syndrome type 10 (JBTS10), and Simpson-Golabi-Behmel syndrome type 2, the latter causing the X-linked syndromic form of PCD. Neurological and skeletal symptoms are characteristic for these syndromes, with their severity depending on the location of the mutation within the gene. OBJECTIVES: To elucidate the role of motile cilia defects in the respiratory phenotype of PCD patients with C-terminal OFD1 mutations. METHODS: Whole-exome sequencing in a group of 120 Polish PCD patients, mutation screening of the OFD1 coding sequence, analysis of motile cilia, and magnetic resonance brain imaging. RESULTS: Four novel hemizygous OFD1 mutations, in exons 20 and 21, were found in men with a typical PCD presentation but without severe neurological, skeletal or renal symptoms characteristic for other OFD1-related syndromes. Magnetic resonance brain imaging in two patients did not show a molar tooth sign typical for JBTS10. Cilia in the respiratory epithelium were sparse, unusually long and displayed a defective motility pattern. CONCLUSION: Consistent with the literature, truncations of the C-terminal part of OFD1 (exons 16-22) almost invariably cause a respiratory phenotype (due to motile cilia defects) while their impact on the primary cilia function is limited. We suggest that exons 20-21 should be included in the panel for regular mutation screening in PCD.

Nijmegen Breakage Syndrome Complicated With Primary Pulmonary Granulomas.

Nijmegen breakage syndrome (NBS) is a rare autosomal recessive disease characterized by microcephaly, growth retardation, severe immunodeficiency, and predisposition to lymphoid malignancy. In this report, we describe a case of a 9-year-old boy, previously diagnosed with NBS and symptoms of dyspnea, dry cough, and fever. Despite initial recognition of pneumonia, there was no response to broad spectrum antimicrobial treatment, negative results from microbiological tests, and unclear changes in lung imaging were observed. Therefore, further diagnostics were focused on suspected lymphoid malignancy and involved lung biopsy. Unexpectedly, histopathological examination revealed noncaseating granulomas. The introduction of systemic steroids resulted in significant improvement of the patient's clinical condition. This is the first description of primary pulmonary noncaseating granulomas without nodular involvement in a child with NBS.

Matrix metalloproteinase 9 in exhaled breath condensate in patients with stable chronic obstructive pulmonary disease: an observational study.

Introduction Data on the measurement of matrix metalloproteinase 9 (MMP­9) in exhaled breath condensate (EBC) from patients with chronic obstructive pulmonary disease (COPD) are scarce and inconsistent. Objectives We aimed to assess the usefulness of enzyme­linked immunosorbent assay (ELISA) and immunoenzymatic assay (IEA) for the measurement of MMP­9 in EBC, the agreement between the results of both methods, and the relationships between total and active MMP­9 in EBC and clinical and functional COPD characteristics. Patients and methods Total (ELISA and IEA) and active (IEA) MMP­9 levels were assessed in EBC from 70 patients with stable COPD and 21 controls and correlated with pulmonary function and COPD symptom severity. Results MMP­9 levels did not reach the sensitivity threshold of the ELISA kit in any of the COPD patients and in 11 controls. Total and active MMP­9 (IEA) levels did not differ between COPD patients and controls. In COPD patients, total MMP­9 levels correlated positively with forced expiratory volume in 1 second (FEV1) and FEV1 to forced vital capacity ratio and inversely with residual volume to total lung capacity ratio. A weak positive correlation between active MMP­9 concentrations and COPD Assessment Test (CAT) score was found (r = 0.31, P = 0.01). Conclusions The utility of ELISA in MMP­9 assessment in EBC is limited in COPD patients, while MMP­9 measurement in EBC by IEA is feasible. The positive correlation between active MMP­9 and CAT score in our patients and the inverse relationship between total MMP­9 concentration and the degree of airway obstruction reflect the complex role of MMP­9 in COPD.

Polymorphic Variants 279R and 668Q Augment Activity of Matrix Metalloproteinase-9 in Breath Condensates of Children with Asthma.

Matrix metalloproteinase (MMP)-9 is involved in pathophysiology of asthma, mainly asthma-associated airway remodeling. Exhaled breath condensates (EBC) of asthmatics contain increased amounts of MMP-9 with activity higher, than in healthy controls. The increased activity of MMP-9 may originate from its excessive production and activation, but may also result from variations in MMP-9 structure, which are determined by single nucleotide polymorphisms (SNPs). In this pilot study we aimed to assess the possible influence of two functional MMP-9 polymorphisms, Q279R and R668Q, on enzymatic activity of MMP-9, measured in EBC of asthmatic children. The concentration and activity of MMP-9 were analyzed in EBC of 20 children with allergic asthma using specific standard ELISA and novel immunoenzymatic activity assay. The SNPs of MMP-9 were assessed using real-time PCR-based genotyping test. We have found that MMP-9 concentration in breath condensates of children with stable asthma was slightly higher in ELISA, than in the activity assay. Moreover, these results and activity-to-amount ratio have revealed some relationship with a presence of specific 279R and/or 668Q MMP-9 gene variants. Our observation suggests that at least in some patients MMP-9 hyperactivity may result from genetic predisposition, determined by polymorphic variants of MMP-9 gene. Moreover, it supports previous reports postulating significance of MMP-9 in pathogenesis of asthma. However, this issue still requires further studies.

Increased angiogenic factors in exhaled breath condensate of children with severe asthma - New markers of disease progression?

Asthma progression is associated with airway remodeling and neo-vascularization. However, role of angiogenesis in these changes remains unclear and available data still incomplete. In this pilot study we verify usefulness of proteome profiler assay in screening of angiogenesis-related factors in exhaled breath condensates (EBC) collected from children with asthma. EBC samples from patients with mild or severe asthma and healthy controls were tested using protein array. In EBC samples from patients with severe asthma we have found large quantities of several angiogenesis regulators, including thrombospondin (TSP)-1, angiogenin, dipeptidyl peptidase (DPP) IV, matrix metalloproteinase (MMP)-9 and its inhibitor TIMP-1. Small amounts of angiopoietin (Ang)-2 and vascular endothelial growth factor (VEGF) were also present. In contrast to them, in EBC from mild asthma group we have detected TSP-1 and small quantities of Ang-2. EBC samples from healthy controls contained only TSP-1. Our preliminary report suggests that, since increased amounts of angiogenesis-related factors in EBC seem to correlate with asthma severity, they may be considered as convenient non-invasive markers of disease progression. However, further research is necessary.

Inhaled corticosteroids do not reduce initial high activity of matrix metalloproteinase (MMP)-9 in exhaled breath condensates of children with asthma exacerbation: a proof of concept study.

Inhaled corticosteroids (ICS) are the key component of asthma treatment. However, it is unclear whether they could control the activity and level of matrix metalloproteinase (MMP)-9, which is an important factor in asthma-associated inflammation and airway remodeling. Therefore, the aim of this proof of concept study was to analyze the influence of increased doses of ICS on MMP-9 in exhaled breath condensates (EBC) of patients with allergic asthma exacerbation. Apart from MMP-9, the assessment concerned selected inflammation markers - exhaled nitric oxide (eNO) and cytokines (IL-8 and TNF). The study involved a small group (n = 4) of individuals with asthma exacerbation. The intervention concerned increased doses of ICS with ß-mimetics for 4 weeks. In addition to clinical evaluation, eNO measurements and EBC collections were done before and after 4 weeks of intense ICS treatment. The biochemical assessment of EBC concerned MMP-9, IL-8 and TNF. The data were compared to results of healthy controls (n = 6). The initial levels of eNO, MMP-9 and TNF in EBC were higher in the asthma group than in controls. In all subjects IL-8 levels were below the detection limit. After 4 weeks of ICS treatment in all patients we observed improvement of clinical and laboratory parameters. Interestingly, despite reduction of eNO and TNF, the activity of MMP-9/EBC remained on the initial level. Practical relevance of our results is limited by a small group. Nevertheless, our data suggest that ICS, although sufficient to control symptoms and inflammatory markers, may be ineffective to reduce MMP-9/EBC activity in asthma exacerbation and, possibly, airway remodeling.

Airway Remodeling in Chronic Obstructive Pulmonary Disease and Asthma: the Role of Matrix Metalloproteinase-9.

Chronic obstructive pulmonary disease (COPD) and asthma are both associated with airflow restriction and progressive remodeling, which affect the respiratory tract. Among various biological factors involved in the pathomechanisms of both diseases, proteolytic enzymes--matrix metalloproteinases (MMPs)--play an important role, especially MMP-9. In this review, the authors discuss the current topics of research concerning the possible role of MMP-9 in both mentioned diseases. They include the analysis of protein levels, nucleotide polymorphisms of MMP-9 gene and their possible correlation with asthma and COPD. Finally, the authors refer to the studies on MMP-9 inhibition as a new perspective for increasing the effectiveness of treatment in asthma and COPD.

Prolonged Treatment with Inhaled Corticosteroids does not Normalize High Activity of Matrix Metalloproteinase-9 in Exhaled Breath Condensates of Children with Asthma.

The airway remodeling in asthma is associated with increased amount of matrix metalloproteinase (MMP)-9. High levels of MMP-9 were found in mucosal biopsies, sputum and in exhaled breath condensates (EBC) of asthma patients. However, there are no data concerning real in vivo activity. Inhaled corticosteroids are effective in asthma control, but it is unclear, whether they only attenuate inflammation, or also protect against progressive remodeling of respiratory tract. Therefore, the aim of the study was to assess the amount and activity of MMP-9 in context of pro-inflammatory cytokines (IL-6, IL-8 and tumor necrosis factor, TNF), measured in EBC of asthma-suffering children, treated with inhaled steroids. The study involved 27 children with asthma, continuously treated with inhaled fluticasone propionate, and 22 healthy controls. In addition to routine clinical screening, the selected cytokines in EBC were analyzed using Ultrasensitive ELISA, whereas activity of MMP-9 was assessed using a novel immunozymography method. Despite chronic treatment with inhaled steroids mean MMP-9/EBC activity in asthma group was significantly higher than in healthy controls. Moreover, high MMP-9/EBC in asthma-suffering children significantly correlated with IgE serum levels. The IL-6 and IL-8 concentration was below the detection limit in all EBC samples. TNF/EBC levels were similar in both, asthma and healthy children. We hypothesize that MMP-9 hyperactivity in asthma may be closely related to high IgE serum levels. Our results suggest that inhaled steroids may be ineffective to prevent asthma-associated airway remodeling. Finally, we emphasize the necessity of further research focused on MMP-9 inhibition in asthma treatment.

Nitric oxide, IL-6 and IL-13 are increased in the exhaled breath condensates of children with allergic rhinitis.

AIM: To evaluate nitric oxide and interleukin (IL)-6, IL-8 and IL-13 in the exhaled breath of children with allergic rhinitis (AR), before and after intranasal allergen exposure. METHODS: A total of 49 children with AR ­ comprising 20 who also had episodic asthma (AR+A) and 29 without asthma (AR) ­ were compared with 34 healthy controls. Nitric oxide concentrations in exhaled air (eNO) and IL-6, IL-8 and IL-13 in exhaled breath condensates (EBC) were measured in winter, outside the natural allergen exposure season, before and after an intranasal allergen challenge. RESULTS: The mean concentrations of eNO, IL-6 and IL-13 were significantly higher in the two AR groups. The concentration of IL-8 was below the assay detection limit in all EBC samples. The intranasal allergen challenge increased IL-13/EBC levels in both AR groups, but did not influence mean concentrations of eNO, IL-6 or IL-8. No challenge-related changes in IL-13/EBC were observed in the allergen-exposed controls or placebo-exposed children. CONCLUSION: Despite local application, the intranasal allergen challenge increased IL-13/EBC concentration in the AR children. As EBC reflects the status of lower airway segments, our observation may support the 'united airways' hypothesis, suggesting a functional link between the upper and lower airways.