@article {Omony4023, author = {Jimmy Omony and Ruth Grychtol and Nicole Maison and Dominik Thiele and Adan Chari Jirmo and Anna-Maria Dittrich and Thomas Bahmer and Klaus. F Rabe and Harald Renz and Gesine Hansen and Matthias Kopp and Bianca Schaub and Erika Von Mutius and Sabina Illi}, title = {The role of eosinophils in pediatric and adult asthma}, volume = {56}, number = {suppl 64}, elocation-id = {4023}, year = {2020}, doi = {10.1183/13993003.congress-2020.4023}, publisher = {European Respiratory Society}, abstract = {Background: In adults, asthma is typically classified as Th2-high/Th2-low based on Th2-inflammation markers like eosinophils. In children, it is mostly characterized by atopy.Aim: We assess whether Th2 asthma phenotypes based on eosinophils and if atopy can be defined in children (as in adults).Methods: In the ALL-Age-Asthma-Cohort (ALLIANCE), blood eosinophils and specific IgE (sIgE) were assessed in 149 wheezers (7mos{\textendash}6yrs), 194 asthmatic children (6-18yrs) and 210 asthmatic adults. We defined atopy as any sIgE>=0.7 IU/mL. Eosinophil cutoffs were determined as the 90th percentile of the absolute eosinophil counts in age-matched healthy controls. Phenotypes were defined using low/high eosinophils and atopy.Results: The prevalence of phenotypes (Th2-low, Eos-only, Atopy-only, Th2-high) was 49.0\%, 15.4\%, 18.8\%, 16.8\% in wheezers; 19.1\%, 1.5\%, 42.3\%, 37.1\% in asthmatic children and 17.1\%, 18.6\%, 33.8\%, 30.5\% in adults. In adults, exacerbations were mostly in the Eos-only phenotype (64.1\%) compared to 35.9\% and 26.8\% in Th2-high and Atopy-only phenotypes (p=0.001). In contrast, in asthmatic children, wheezing episodes were most frequent in the Th2-high phenotype (50.7\%) compared to 34.1\% in the Atopy-only phenotype (p=0.017). Those with Eos-only were too few for analysis. In wheezers, phenotypes based on eosinophils and atopy had no association with wheezing. However, both atopic groups with/without high eosinophils had the highest risk of asthma at 6yrs (78.9\% and 72.7\%) compared to the only eosinophilic group (41.7\%, p=0.002).Conclusion: It is unclear if the Th2-phenotype as is described in adults exists in children. Eosinophils possibly play a different role in children.FootnotesCite this article as: European Respiratory Journal 2020; 56: Suppl. 64, 4023.This abstract was presented at the 2020 ERS International Congress, in session {\textquotedblleft}Respiratory viruses in the "pre COVID-19" era{\textquotedblright}.This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).}, issn = {0903-1936}, URL = {https://erj.ersjournals.com/content/56/suppl_64/4023}, eprint = {https://erj.ersjournals.com/content}, journal = {European Respiratory Journal} }