Induction of apoptosis in bronchial eosinophils: beneficial or harmful?

Background: Prominent eosinophil infiltration takes place in asthmatic bronchi, and damages bronchial epithelial cells.

Aim: This study was designed to investigate whether induction of apoptosis in infiltrated cells in the airways is beneficial or harmful.

Methods: A/J mice, which are genetically predisposed to be hyperresponsive to acetylcholine, were immunized with ovalbumin (OA) and alum. Thereafter, they were subjected to a 2-week regimen of OA inhalation, during which they were also administered either hamster anti-mouse Fas monoclonal antibody or hamster IgG (sham control) intranasally. Pulmonary function was then analyzed using whole-body plethysmography.

Results: Inhalation of OA increased both airway responsiveness to acetylcholine and infiltration of eosinophils. Administration of anti-Fas antibody induced apoptosis in the infiltrating eosinophils and abolished the increase in airway responsiveness to acetylcholine.

Conclusion: Induction of apoptosis in eosinophils infiltrating asthmatic bronchi has a beneficial effect on airway hyperresponsiveness.