IgE sensitisation in relation to flow-independent nitric oxide exchange parameters

Andrei Malinovschi,Dan Norbäck,Thomas Holmkvist,Pekka Meriläinen,Christer Janson,Marieann Högman

doi:10.1186/1465-9921-7-92

Andrei Malinovschi, Dan Norbäck + Show 4 more

Open Access

https://doi.org/10.1186/1465-9921-7-92

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Abstract

BackgroundA positive association between IgE sensitisation and exhaled NO levels has been found in several studies, but there are no reports on the compartment of the lung that is responsible for the increase in exhaled NO levels seen in IgE-sensitised subjects.MethodsThe present study comprised 288 adult subjects from the European Community Respiratory Health Survey II who were investigated in terms of lung function, IgE sensitisation (sum of specific IgE), smoking history and presence of rhinitis and asthma. Mean airway tissue concentration of NO (CawNO), airway transfer factor for NO (DawNO), mean alveolar concentration of NO (CalvNO) and fractional exhaled concentration of NO at a flow rate of 50 mL s-1 (FENO 0.05) were determined using the extended NO analysis.ResultsIgE-sensitised subjects had higher levels (geometric mean) of FENO 0.05 (24.9 vs. 17.3 ppb) (p < 0.001), DawNO (10.5 vs. 8 mL s-1) (p = 0.02) and CawNO (124 vs. 107 ppb) (p < 0.001) and positive correlations were found between the sum of specific IgE and FENO 0.05, CawNO and DawNO levels (p < 0.001 for all correlations). Sensitisation to cat allergen was the major determinant of exhaled NO when adjusting for type of sensitisation. Rhinitis and asthma were not associated with the increase in exhaled NO variables after adjusting for the degree of IgE sensitisation.ConclusionThe presence of IgE sensitisation and the degree of allergic sensitisation were related to the increase in airway NO transfer factor and the increase in NO concentration in the airway wall. Sensitisation to cat allergen was related to the highest increases in exhaled NO parameters. Our data suggest that exhaled NO is more a specific marker of allergic inflammation than a marker of asthma or rhinitis.

Highlights

A positive association between IgE sensitisation and exhaled nitric oxide (NO) levels has been found in several studies, but there are no reports on the compartment of the lung that is responsible for the increase in exhaled NO levels seen in IgE-sensitised subjects
IgE sensitisation IgE sensitisation was associated with higher levels of fractional exhaled nitric oxide (FENO) 0.05, CawNO and DawNO (Table 2)
The associations with FENO 0.05 and DawNO remained significant after adjusting for potential confounders (Table 2)

Summary

Introduction

A positive association between IgE sensitisation and exhaled NO levels has been found in several studies, but there are no reports on the compartment of the lung that is responsible for the increase in exhaled NO levels seen in IgE-sensitised subjects. An increase in exhaled nitric oxide (NO) levels due to IgE sensitisation was first observed in laboratory animal allergy [1] and asymptomatic atopic subjects[2]. A positive association between exhaled NO levels and the degree of IgE sensitisation has been found both in children [3,4,5,6] and in the adult population [7]. Non-asthmatic subjects often have a subclinical airway inflammation[10] This eosinophilic inflammation causes lung tissue damage followed by the release of cytokines and the stimulation of inducible nitric oxide synthase (iNOS). The increase in epithelial iNOS activity probably explains the increase in NO levels in IgE-sensitised subjects, since epithelial iNOS activity has been shown to be the main determinant of FENO in humans[13]

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