Neutrophil defensins: their possible role in allergic asthma

Neutrophil defensins, originally identified as broad-spectrum antimicrobial peptides, have been implicated in the regulation of inflammatory and immunological processes. To investigate whether the in vitro challenge of neutrophils from patients with bronchial asthma with allergens stimulated the release of alpha-defensins and whether levels released were dependent on lung infections. The neutrophils were cultivated with different agonists and the concentration of alpha-defensin in cell-free supernatant was measured with enzyme-linked immunosorbent assay (ELISA). Neutrophils from allergic patients released alpha-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 alpha-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 alpha-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 alpha-defensin under respiratory tract infection than cells from the same patients without such an infection. Neutrophils from allergic patients release alpha-defensins via an allergen-dependent mechanism.