From:  Evidence-based answers to clinical controversies in the management of severe asthma

 Key distinguishing features between type 2 (T2) and no-T2 or low-T2 asthma

High-T2 asthmaType no-T2 or low-T2 asthma
Associated with eosinophilic inflammationAssociated with neutrophilic or pauci-granulocytic inflammation
Driven by Th2-type cytokines (IL-4, IL-5, IL-13)Driven by other inflammatory pathways (e.g., IL-17, IL-8)
Often has elevated IgE levelsIgE levels are usually normal or low
More likely to be responsive to corticosteroidsOften resistant or less responsive to corticosteroids
Common in allergic asthma and late-onset eosinophilic asthmaCommon in obese patients, smokers, and the elderly
Biomarkers: FeNO, blood eosinophils, periostinBiomarkers: none well established or under investigation
Targeted by biologic therapies (e.g., anti-IL-5, anti-IL-4R)Few targeted treatments are currently available
Often diagnosed via biomarker analysisDiagnosis often relies on clinical assessment and exclusion
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FeNO: fractional exhaled nitric oxide; IL-4: interleukin-4