The inflammatory response of eosinophil-related fungal rhinosinusitis varies with inciting fungi

Abstract

Earlier studies demonstrated immunological response to Alternaria alternata in patients with eosinophil-related fungal rhinosinusitis (FRS). However, Aspergillus flavus rather than A. alternata is predominantly isolated from such patients in Asia. We compared immunological response to A. flavus and A. alternata in our patients with eosinophil related FRS. Total immunoglobulin E, absolute eosinophil count (AEC), cytokine response, and in vitro eosinophil degranulation in the presence of A. flavus/A. alternata were compared among patients with eosinophil-related FRS, non-eosinophilic rhinosinusitis (NECRS), and healthy individuals. Eosinophil-related FRS patients were subgrouped into: Group A - presence of mucin with fungus in tissues and positive immediate hypersensitivity; group B - presence of mucin with fungus in biopsies and no immediate hypersensitivity; and group C - presence of mucin without fungi and hypersensitivity. A. flavus was the predominant (89%) isolate. Significantly higher major basic protein (MBP) was induced by A. flavus in Group A (279.15 ± 32.29 ng/2.5 × 10(5) cells) compared to Group B (254.9 ± 17.14 ng), Group C (238.33 ± 17.56 ng), NECRS (56.96 ± 10.97 ng), and normal subjects (28.73 ± 7.04 ng). A. alternata - eosinophil interaction failed to induce detectable MBP. AEC and serum cytokines, interleukin (IL)- 2, IL-4, IL-5, IL-10, tumor necrosis factor α, and interferon-γ were significantly higher (P < 0.001) in eosinophil-related FRS compared to NECRS and control. Thus a mixed Th1 and Th2 cytokine response was observed in eosinophil-related FRS. In conclusion, immune response in eosinophil-related FRS depends on locally inciting fungi rather than A. alternata in all instances, and the categorization of this group appears to be arbitrary.

Keywords: Alternaria alternata; Aspergillus flavus; allergy; cytokines; eosinophils; fungal rhinosinusitis.