Bronchial challenge with D. pteronyssinus changes the ratio of blood eosinophil subtypes and their biological properties in allergic asthma patients

Abstract

Introduction: Acute allergic asthma (AA) attack is associated with eosinophilic airway inflammation. We presumed that distinct eosinophil subtypes - lung-resident (rEOS) and inflammatory (iEOS) eosinophils, may differently respond during allergen provoked asthma episode

Aim: To investigate the effect of allergen challenge to blood rEOS and iEOS ratio as well as their adhesion and viability in AA patients

Methods: 8 steroid-free AA patients, sensitized to Dermatophagoides pteronyssinus, and 8 healthy subjects (HS) were investigated. Allergen challenge was performed for all study subjects. Blood EOS before and 24 h after allergen challenge were isolated by high-density centrifugation and magnetic separation, phenotyping - with antibodies against CD62L. EOS adhesion to airway smooth muscle (ASM) cells was measured by evaluating EOS peroxidase activity; EOS viability - by annexin V and PI staining

Results: At baseline, the predominant eosinophil subtype in AA patients was iEOS with the rEOS:iEOS ratio (RIR) of 0.59 while in HS group RIR was 0.93. rEOS showed increased adhesion to ASM cells compared with iEOS by 14.7±2.9% in AA group and 17.2±2.0% in HS group (p<0.05). Adhesion was directly related to the viability of only rEOS (p<0.05) in both groups. After the allergen challenge, the RIR in AA patients increased up to 0.93 (p<0.05) without significant change in HS group. Allergen challenge enhanced only iEOS viability in AA group (p<0.05) but did not affect the adhesion of EOS subtypes in both groups

Conclusion: Allergen challenge increased the RIR and prolonged iEOS viability without effect on adhesion of both EOS subtypes in AA patients