SERUM ANTI-ASPERGILLUS FUMIGATUS ANTIBODIES BY IMMUNOBLOT AND ELISA IN CYSTIC-FIBROSIS WITH ALLERGIC BRONCHOPULMONARY ASPERGILLOSIS

Allergic bronchopulmonary aspergillosis (ABPA) occurs with a prevalenc e of 5% to 15% in patients with cystic fibrosis (CF). Because of the f requent colonization with Aspergillus fumigatus (Af) in CF; the causat ive agent of ABPA, antibody reactivity to Af proteins is frequently ob served, which obscures the diagnosis of ABPA. Patients with CF are als o categorized according to the presence of positive skin test response s to Af and/or the presence of positive precipitins. In this study we used ELISA and immunoblot assay to detect IgE and IgG anti-Af antibodi es in patients with CF and ABPA (n = 13) compared with other groups of patients with CF: those with positive skin test and positive precipit in results (n = 18), those with positive skin test and negative precip itin results (n = 14), those with negative skin test and positive prec ipitin results (n = 10), and those with negative skin test and negativ e precipitin results (n = 35). IgE and IgG anti-Af antibodies were sig nificantly elevated in patients with ABPA as determined by both immuno blot assay (p < 0.01) and ELISA (p < O.01). However, detection of Af a ntibodies by ELISA was more sensitive in discriminating patients with CF and ABPA from patients with CF who had positive skin test and posit ive precipitin results but lacked radiographic and clinical evidence o f ABPA. In patients with CF and ABPA the immunoblot assays demonstrate d a multitude of IgE, IgG, and IgA antibody responses to Af proteins w hich ranged in molecular weight from 14 kd to greater than 106 kd. The level of IgE anti-Af antibody to individual proteins decreased during remissions of ABPA. IgG and IgA anti-Af antibodies, however once deve loped did not decrease nearly as much.