Background: Neutrophil defensins, originally identified as broad-spectrum antimicrobial peptides, have been implicated in the regulation of inflammatory and immunological processes.

Objectives: To investigate whether the in vitro challenge of neutrophils from patients with bronchial asthma with allergens stimulated the release of α-defensins and whether levels released were dependent on lung infections.

Method: The neutrophils were cultivated with different agonists and the concentration of α-defensin in cell-free supernatant was measured with enzyme-linked immunosorbent assay (ELISA).

Results: Neutrophils from allergic patients released α-defensins via an allergen-dependent mechanism. Our results indicate that the in vitro activation of neutrophils is highly allergen-specific. In this context, allergens other than those which produced clinical symptoms did not elicit α-defensin release, and allergens had no effect on neutrophils from healthy donors. However, neutrophils from both allergic patients and healthy controls were able to release α-defensins upon treatment with PMA. In the allergen-stimulated neutrophils, cells from asthmatic patients stimulated with a sensitizing allergen showed a significantly higher production of α-defensin under respiratory tract infection than cells from the same patients without such an infection

Conclusion: Neutrophils from allergic patients release α-defensins via an allergen-dependent mechanism.

Key words: Neutrophil. IgE. Allergy. Alpha defensins. Allergen challenge. Asthma.