Recombinant Aspergillus fumigatus-specific IgE for monitoring treatment response and detecting exacerbations in allergic bronchopulmonary aspergillosis.

Abstract

Serum total IgE is the preferred biomarker for monitoring disease activity in allergic bronchopulmonary aspergillosis (ABPA). The utility of IgE directed against recombinant Aspergillus fumigatus antigens (rAsp-IgE) for monitoring treatment response and detecting exacerbations in ABPA remains unknown. To evaluate longitudinal changes in rAsp-IgEs during treatment of ABPA, compare their performance with serum total IgE and crude A. fumigatus-specific IgE (cAsp-IgE), and assess the utility of rAsp-IgEs for detecting ABPA exacerbations. We prospectively enrolled consecutive adults with ABPA. Serum total IgE, cAsp-IgE, and rAsp-IgEs (f 1, f 2, and f 4) were measured at baseline, 2, and 4 months of treatment. We assessed the proportion of participants achieving a ≥20% decline in each biomarker. Participants were followed for 12 months to identify exacerbations and evaluate biomarker behaviour. Among 122 enrolled participants, 119 and 107 completed the 2- and 4-month assessments. Serum total IgE and all three rAsp-IgEs declined significantly at both timepoints, whereas cAsp-IgE showed no significant decline. A ≥20% decline in at least one rAsp-IgE occurred more frequently than serum total IgE at two (91.6% vs. 77.1%; p=0.003) and four months (88.8% vs. 74.8%; p=0.007). Fifteen participants experienced exacerbations; rAsp f 4-IgE increased in all events (100%) compared with total IgE (12/15, 80%), rAsp f 1 -IgE (7/15, 46.7%), and rAsp f 2-IgE (6/15, 40%). rAsp-IgEs demonstrated significant longitudinal declines during ABPA treatment, while rAsp f4-IgE consistently increased during exacerbations. Larger multicenter prospective studies are warranted to define their role in disease monitoring.