Blood eosinophil count (BEC), immunoglobulin E (IgE), and fractional exhaled nitric oxide (FeNO) are key clinical indicators for identifying type 2 (T2) asthma.
To provide optimal cutoff points of T2 markers for assessing T2-high or uncontrolled asthma in real-world practice.
Various clinical and laboratory parameters were analyzed according to the result of T2 markers (BEC, serum free IgE, and FeNO) in adult asthmatics who had maintained anti-asthmatic medications. Their cutoff levels for representing uncontrolled asthma were determined using receiver operating characteristic (ROC) analysis. Blood levels of periostin and eosinophil-derived neurotoxin (EDN) were measured by ELISA. Activation markers of circulating eosinophils (siglec8+) and neutrophils (CD66+) were analyzed by flow cytometry.
Of 133 asthmatic patients, 23 (17.3%) had 3 T2 markers (BEC ≥ 300 cells/μL, serum free IgE ≥ 120 ng/mL, and FeNO ≥ 25 ppb) and significantly higher levels of sputum eosinophils/blood EDN/siglec8+ eosinophils, but lower FEV1% as well as higher rate of uncontrolled status (P < .05 for all). In addition, patients with uncontrolled asthma had significantly higher levels of FeNO/BEC with lower FEV1% (P < 0.05 for all). The optimal cutoff values for predicting uncontrolled asthma were found to be 22 ppb of FeNO levels, 161.4 cells/L of BECs, and 85.9 ng/mL of serum-free IgE levels.
We suggest the optimal cutoff values of BEC, IgE, and FeNO for classifying T2-high or uncontrolled asthma, which could be applied as candidate biomarkers for targeting asthmatics who require T2-biologics.

Copyright © 2023. Published by Elsevier Inc.