Serum Mannose-Binding Lectin Levels in Asthma and Allergic Bronchopulmonary Aspergillosis

Mannose-binding lectin (MBL) contributes to innate immunity against Aspergillus fumigatus. We assessed the role of reduced MBL levels in asthma patients with and without allergic bronchopulmonary aspergillosis (ABPA). In this prospective cross-sectional study, we enrolled 154 adults: 48 with asthma, 27 with Aspergillus-sensitized asthma (ASA, A. fumigatus-IgE ≥ 0.35 kUA/L), and 79 with ABPA. Serum MBL levels were quantified using enzyme-linked immunosorbent assay. Reduced MBL levels were defined using three thresholds (< 200, < 359, and < 500 ng/mL). The prevalence of reduced MBL levels did not differ significantly among the groups at any threshold. However, mean MBL levels were significantly lower in patients with ABPA (961 ng/mL) compared to asthma (1159 ng/mL) and ASA (1593 ng/mL; p = 0.048). Among ABPA patients, reduced MBL levels (≤ 359 ng/mL) were not associated with significant differences in clinical features, immunological markers, lung function, or radiology.