RT Journal Article SR Electronic T1 ILC2 cells from severe allergic and eosinophilic asthma demonstrate increased expression of TSLP receptor (TSLPR) and enhanced proliferative capacity JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP PA823 DO 10.1183/13993003.congress-2021.PA823 VO 58 IS suppl 65 A1 Bilal Malik A1 Rebecca Mckerrow A1 John Harrington A1 John W. Upham A1 Nathan Bartlett A1 Peter Ab Wark YR 2021 UL http://erj.ersjournals.com/content/58/suppl_65/PA823.abstract AB Background: It is evident that group 2 innate lymphoid cells (ILC2s) play an important role in asthma by promoting type 2 inflammation.Aims: To compare ILC2s proliferation and cytokine secretion between severe allergic and eosinophilic asthma (SA), mild asthma (MA), healthy controls (HC) and allergic controls without asthma (AC).Methods: HC and AC subjects had normal lung function and no history of asthma. MA subjects had GINA step 1 or 2 asthma. SA subjects had GINA step 5 severe eosinophilic and allergic asthma. All SA subjects were on high dose of inhaled corticosteroids median (Q1, Q3) 1440 (800, 2200) (mcg/d). Peripheral blood mononuclear cells (PBMCs) were obtained from HC n=10, AC n=10, MA n=10 and SA n=10. ILC2s were identified and sorted by flow cytometer, cultured for 14 days with IL-2, IL-33, IL-25 and TSLP. ILC2s proliferative capacity was assessed by Ki-67 expression, surface receptors and secretion of IL-5 and IL-13 by flow cytometer on day 14 of culture. Significance was calculated using 1-way ANOVA while correlation analysis was done using Pearson test.Results: At day 14 of culture, ILC2s from SA demonstrated increased TSLPR expression (p=<0.0001), Ki-67 expression (p=<0.0001) and cytokine release of IL-5 (p=<0.0001) and IL-13 (p=<0.0001) compared to ILC2s from HC, AC and MA. Increased TSLPR expression in SA positively correlated with Ki-67 expression (R2 = 0.75; p=<0.0001), IL-5 release (R2 = 0.63; p=<0.0001) and IL-13 release (R2 = 0.59; p=<0.0001).Conclusion: ILC2s from SA subjects demonstrate increased TSLPR expression that significantly correlated with increased proliferative capacity and secretion of IL-5 & IL-13FootnotesCite this article as: European Respiratory Journal 2021; 58: Suppl. 65, PA823.This abstract was presented at the 2021 ERS International Congress, in session “Prediction of exacerbations in patients with COPD”.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).