Allergic Bronchopulmonary Aspergillosis/Mycosis: An Allergic Disease or an Eosinophilic Disease?

Allergic bronchopulmonary aspergillosis/mycosis (ABPA/ABPM) is characterized by increased serum levels of total and fungi-specific immunoglobulin E (IgE) and eosinophilic mucus plugs in the airways. Its classification as either an allergic or eosinophilic disease remains controversial. In the present review, we explored this topic based on three clinical studies that analyzed the clinical characteristics of ABPA/ABPM using a cluster analysis, factor analysis, and comparison between ABPM caused by Schizophyllum commune and ABPA. We also compared therapeutic responses to biologics targeting either IgE (omalizumab) or eosinophils (mepolizumab/benralizumab) to elucidate the role of these components in the pathogenesis of ABPA/ABPM. Based on these analyses, eosinophilic mucus plug formation in the airways is considered a cardinal feature of the development of ABPA/ABPM, whereas IgE responses to fungi are important factors that modulate disease manifestation.