Purpose: The diagnosis of Aspergillosis in Cystic Fibrosis (CF) patients remains a challenge due to overlapping features of both diseases. This is further complicated by inconsistent antibody reactivity to the currently used crude antigen, which has led a more focused evaluation of the efficacy of IgE response to a number of pure Aspergillus fumigatus recombinant proteins in patients with CF and asthma. In this study, we dissected the IgE and IgG responses to multiple A. fumigatus recombinant antigens in CF patients with different Aspergillus diseases.

Methodology: Serum IgE and IgG antibodies against Asp f1, Asp f2, Asp f3, Asp f4 and Asp f6 were measured in CF patients with Allergic Bronchopulmonary Aspergillosis (ABPA) (n=12), using ImmunoCAP technique. The results were compared to serum IgE levels in patients with Aspergillus sensitization (n=12), and serum IgG levels in patients with Aspergillus bronchitis (n=12).

Results: The ABPA group showed significantly greater IgE response to Asp f1, f2, f3 and f4 compared to Aspergillus sensitization group. Patients with Aspergillus bronchitis expressed higher IgG positivity to Asp f1 and Asp f2 compared to those with ABPA. There were very low IgE antibody levels against all recombinant antigens in patients with Aspergillus sensitization. Aspf1 IgG reactivity in ABPA patients correlated with positive culture.

Conclusion: The use of multiple recombinant antigens might improve the diagnostic accuracy in patients with cystic fibrosis complicated with ABPA or Aspergillus bronchitis. Asp f1 reactivity may relate to the presence of actively growing Aspergillus spp., which might be a useful marker for guiding antifungal therapy in ABPA.

Keywords: Recombinant antigens, Serology, Aspergillus, Asp f1, ABPA, Cystic fibrosis

Abbreviations: CF: Cystic Fibrosis; ABPA: Allergic Bronchopulmonary Aspergillosis