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

Abstract

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.

Keywords: allergic bronchopulmonary aspergillosis; allergic bronchopulmonary mycosis; biologics; eosinophils; immunoglobulin E.

Figure 1.

Factor scores in allergic bronchopulmonary aspergillosis (ABPA) with atopic or non-atopic, and sans asthma. Factor scores for the allergic (A), eosinophilic (B), and fungal (C) components were compared between patients with ABPA sans asthma (n=25), ABPA with atopic asthma (n=57), and ABPA with non-atopic asthma (n=24). ** p<0.01, **** p<0.0001. (Adopted from equation (20) with permission).

Figure 2.

Treatment targets of allergic bronchopulmonary aspergillosis (ABPA). The clinical presentation of ABPA is characterized by allergic, eosinophilic, and fungal components. The eosinophilic component is a cardinal feature of ABPA, and mepolizumab/benralizumab treatment is often effective. In cases with high scores for the allergic component, treatments targeting both the allergic and eosinophilic components, such as dupilumab or tezepelumab are required.