Serological analysis of sensitization in allergic bronchopulmonary aspergillosis: a study on allergen components and interspecies relationships

Abstract

<b>Background:</b> Serological testing for immunoglobulin (Ig) E or IgG is useful for diagnosing allergic bronchopulmonary aspergillosis (ABPA), as it detects type I and III allergic reactions to <i>Aspergillus</i> species. However, few reports have investigated the allergen component and cross-reactivity among <i>Aspergillus</i> species. We aimed to measure and analyze the levels of IgGs specific to each <i>Aspergillus</i> species and investigate the prevalence of IgEs specific to each allergen component of <i>A. fumigatus</i> (Af) in ABPA patients.<b>Methods:</b> Serum samples were collected from 12 ABPA patients who visited our hospital between February and December 2017, and 16 with Af-sensitized asthma and 41 with Af-unsensitized asthma were controls. Immuno-CAP was performed to analyze the IgEs and IgGs specific to Af, <i>A. niger</i>, <i>A flavus</i> and <i>A. terreus</i>, and IgEs specific to allergen components Asp f 1, 2, 3, 4 and 6.<b>Results:</b> The ABPA group was significantly more frequently sensitized to Asp f 1 and 2 than the control groups. Af-specific IgEs were significantly positively correlated to the IgEs specific to <i>A. flavus</i>, <i>A. niger</i> and <i>A. terreus</i>. Af-specific IgGs were positively correlated to the IgGs specific to all the other species.<b>Conclusions:</b> Tests using allergen components were useful for ABPA diagnosis. Both IgE and IgG were highly cross-reactive among the <i>Aspergillus</i> species. There were many patients apart from asthmatic patients with ABPA, who displayed high <i>Aspergillus</i> IgG values.