Rapid clearance of mepolizumab-resistant bronchial mucus plugs in allergic bronchopulmonary aspergillosis with benralizumab treatment

Dear Editor, Allergic bronchopulmonary aspergillosis (ABPA) is an airway disease caused by an allergic reaction to Aspergillus spp., the most common being A. fumigatus. Pathologically, it is characterized by the presence of intrabronchial eosinophilic mucus plugs containing fungal hyphae. Evidence suggests that eosinophils play an important role in the formation and maintenance of mucus plugs in the airways. For example, viscous mucus plugs in the upper and lower airways of ABPA, chronic rhinosinusitis with nasal polyps, and eosinophilic otitis media are abundantly infiltrated by eosinophils. An eosinophil-specific cytolytic process termed extracellular trap cell death (ETosis), characterized by the extracellular release of viscous chromatin, occurs within mucus plugs found in these diseases. Furthermore, some case reports showed the effectiveness of biologics targeting eosinophil function, such as mepolizumab (anti-IL-5 antibody) and benralizumab (IL-5 receptor-α antibody).