Whilst “type-2 high” eosinophilic inflammation is generally highly responsive to inhaled or oral glucocorticosteroids or novel biologicals [4] targeting the type-2 cytokines interleukin (IL)-4, IL-5 and IL-13 [5], 20–30% of people with severe asthma have neutrophilic inflammation that does not respond to these therapies [6]. Here, IL5 is linked to asthma.