Sensitization to recombinant Aspergillus fumigatus allergens in allergic fungal sinusitis

Background: Allergic bronchopulmonary mycosis is primarily caused by Aspergillus fumigatus. Despite similarities, allergic fungal sinusitis (AFS) is thought to be caused by various fungi. Objective: Identify fungal elements in AFS allergic mucin and determine the prevalence of specific immunoglobulin (Ig)E to recombinant A. fumigatus allergens (rAsp) in AFS patients. Methods: Allergic mucin from 17 definitive and 10 probable AFS patients were histologically examined for fungal elements. Sera from 18 definitive AFS patients, 10 probable AFS patients, 6 chronic sinusitis patients, and 5 A. fumigatus-allergic patients were tested for specific IgE to A. fumigatus and five rasps. Results: Ten of the 17 definitive cases had hyphae morphologically resembling Aspergillus or Fusarium spp. One probable AFS patient had similar findings. Of definitive patients, 94% (17 of 18) showed A. fumigatus-specific IgE (≥0.35 kUa/L), and 67% were positive to one or more rAsp. Four of 10 probable patients demonstrated A. fumigatus-specific IgE, and 2 had IgE to one or more rAsp. The definitive group had greater mean A. fumigatus IgE (P < 0.05) versus the probable and chronic sinusitis groups. The definitive group's rate of IgE to the rAsps was statistically greater. All definitive patients with Aspergillus or Fusarium spp. in situ had A. fumigatus-specific IgE, and 7 of 10 had IgE to at least one rAsp. Conclusions: Most definitive AFS patients have A. fumigatus-specific IgE and many have specific IgE to rAsps. Many also demonstrate Aspergillus spp. or Fusarium spp. in situ. Findings suggests that A. fumigatus is an important causative agent in AFS in the southeast United States.