Introduction. Oxidative stress may play an essential role in allergic asthma (AA) pathogenesis. Blood inflammatory-like eosinophils (iEOS-like) and lung resident-like eosinophils (rEOS-like) are distinct in biological properties and could be differently affected by eosinophilopoetins

Aim. To investigate reactive oxygen species (ROS) production by blood eosinophil subtypes after stimulation with IL-3, IL-5 and GM-CSF in allergic asthma

Methods. We included 9 steroid-naive, non-severe AA patients, and 7 healthy control subjects (HS). Blood eosinophils were isolated using high-density Ficoll centrifugation and magnetic separation, then subtyped using magnetic separation against CD62L. Intracellular ROS production in eosinophils was assessed using Dihydrorhodamine-123 with flow cytometer. All AA patients underwent bronchial allergen challenge (BAC) with D. pteronyssinus, and tests were repeated after 24h

Results. ROS production by both blood eosinophil subtypes was enhanced in AA group, p<0.05 compared to HS. After BAC iEOS-like cells ROS production was higher than rEOS-like cells, p<0.05. Incubation with IL-3 and IL-5 promoted ROS production by both eosinophil subtypes in AA group, p<0.05, however GM-CSF only affected iEOS-like cells. Lastly, eosinophilopoetins promoted ROS production by both eosinophil subtypes after BAC, p<0.05, and iEOS-like cells produced more ROS than rEOS-like cells, p<0.05

Conclusions. In AA, IL-3 and IL-5 promote ROS production by both eosinophil subtypes, while GM-CSF stimulates only iEOS-like cells; in vivo allergen activated blood eosinophil subtypes respond to all eosinophilopoetins producing significantly more ROS, especially iEOS-like cells