Characterisation of a cohort of asthmatics with severe concordant eosinophilic disease according to their IgE status

<b>Background:</b> Eosinophilic inflammation has long been associated with asthma. Looking at systemic and airway eosinophilia, we have recently identified a group of patients exhibiting diffuse eosinophilic inflammation (Schleich F. et al. Eur Respir J 2014). Among the mechanisms governing eosinophilic inflammation, IgE mediated mast cell activation is a key event leading to eosinophilia in atopic asthmatics. <b>Methods:</b> We conducted a retrospective study on our asthma clinic database containing more than 1500 patients and identified 139 asthmatics with determination of serum IgE, successful sputum induction and concordant eosinophilic phenotype. This phenotype was defined as a sputum eosinophil count ≥3% and a blood eosinophils concentration ≥400 cells/mm³. Atopy was characterized by the presence of at least one positive specific IgE (&gt;0.35 kU/L) to common aeroallergens. Total serum IgE &gt;113 kU/L was considered as raised IgE. <b>Results:</b> The majority of asthmatics displaying concordant eosinophilic phenotype had a raised total serum IgE and/or atopy (67%). Non IgE mediated concordant eosinophilic asthma was a predominantly a late onset disease, exhibited a more intense airway eosinophilic inflammation (p&lt;0.05), required more often maintenance treatment with oral corticosteroids (p&lt;0.05) but, surprisingly, had a reduced level of bronchial hyperresponsiveness to methacholine (p&lt;0.05) despite similar baseline airway calibre impairment. <b>Conclusion:</b> The more severe airway eosinophilic inflammation in non IgE mediated asthmatics despite similar treatment with ICS and a higher burden of OCS points to a certain corticosteroid resistance in this asthma phenotype.