The absence of serum IgE antibodies indicates non-type 2 disease in young asthmatics.

Abstract

Atopic asthma is associated with elevated type-2 biomarkers such as fraction of exhaled nitric oxide (FeNO) and blood eosinophil (B-Eos) count. However, increased type 2 markers have also been reported in traditionally defined non-atopic asthma. To determine a clinically useful level of IgE sensitization for ruling out type 2 asthma. Asthmatics (N=408; age 10-35years) were analysed using the multi-allergen tests Phadiatop and fx5 (ImmunoCAP). Subjects were grouped based on IgE-antibody concentrations: ≥0.35kUA /L for at least one test (n=326) or <0.35kUA /L for both tests (n=82). Τhe latter group was subsequently divided into 2 groups: IgE 0.10-0.34kUA /L (n=34) and IgE<0.10kUA /L (n=48). The relationships between type 2 biomarkers, and inadequate asthma control (ACT<20), reduced lung function (FEV1 <80%), recent asthma attacks and airway hyperresponsiveness (AHR) to methacholine were determined. In univariate analyses, at least one type 2 marker related to each asthma outcome in subjects with IgE ≥0.35kUA /L. In subjects with IgE 0.10-0.34kUA /L, elevated FeNO related to reduced lung function (P=.008) and B-Eos to AHR (P=.03). No associations were found in subjects with IgE<0.10kUA /L. In multivariate analysis, a relationship between FeNO and reduced lung function remained in subjects with IgE<0.35kUA /L (P=.03). Clinically relevant elevation of type 2 biomarkers was seen in young asthmatics with IgE antibodies <0.35kUA /L, but not those with IgE<0.10kUA /L. It seems possible to define non-type 2 asthma through sensitive IgE-antibody measurement.