Expanded peripheral <scp> CD62L ^low </scp> inflammatory eosinophils in pediatric thunderstorm‐related asthma exacerbations: A single‐center analysis

BACKGROUND: Thunderstorm-related asthma (TA) is a distinct environmental health emergency marked by abrupt surges in asthma exacerbations following thunderstorm events. Although peripheral eosinophilia has been implicated as a risk factor, the phenotypic and functional characteristics of eosinophils contributing to TA remain insufficiently defined. This study aimed to delineate the phenotypic characteristics of circulating eosinophil subsets in pediatric patients experiencing thunderstorm-related asthma exacerbations. METHODS: Children presenting with asthma exacerbations within 24 h of a documented thunderstorm event were enrolled as the TA group (n = 16), whereas age- and sex-matched children with well-controlled asthma served as controls (WA, n = 26). Circulating eosinophil subsets were characterized by flow cytometry, and type-2 cytokines and eosinophil-associated chemokines in serum were quantified by ELISA. In vitro, the blood eosinophils were isolated and stimulated with cytokines (IL-5, IL-3, and GM-CSF) to assess phenotypic changes and mediator secretion. RESULTS: cells, accompanied by elevated production of Eotaxin-1, Eotaxin-2, Eotaxin-3, and IL-13 in the culture supernatant. CONCLUSIONS: iEOS may be beneficial for early identification of children at high risk of thunderstorm-triggered exacerbations and help inform proactive preventive strategies.