Progressive increase of Fcε RI expression across several PBMC subsets is associated with atopy and atopic asthma within school‐aged children

Background: Antigen-specific IgE binds the Fce receptor I (FceRI) expressed on several types of immune cells, including dendritic cells (DCs). Activation of FceRI on DCs in atopics has been shown to modulate immune responses that potentially contribute to asthma development. However, the extent to which DC subsets differ in FceRI expression between atopic children with or without asthma is currently not clear. This study aimed to analyse the expression of FceRI on peripheral blood mononuclear cells (PBMCs) from atopic children with and without asthma, and non-atopic/non-asthmatic age-matched healthy controls. Methods: We performed multiparameter flow cytometry on PBMC from 391 children across three community cohorts and one clinical cohort based in Western Australia. Results: We confirmed expression of FceRI on basophils, monocytes, plasmacytoid and conventional DCs, with higher proportions of all cell populations expressing FceRI in atopic compared to non-atopic children. Further, we observed that levels of FceRI expression were elevated across plasmacytoid and conventional DC as well as basophils in atopic asthmatic compared to atopic non-asthmatic children also after adjusting for serum IgE levels. Conclusion: Our data suggest that the expression pattern of FceRI on DC and basophils differentiates asthmatic from non-asthmatic atopic children. Given the significant immune modulatory effects observed as a consequence of FceRI expression, this altered expression pattern is likely to contribute to asthma pathology in children.