Objective: To determine clinical features of neutropilic asthma, we investigated clinical variables in patients with asthma attending to our hospital regularly.
Methods: Stable patients with bronchial asthma with maintenance treatment underwent sputum induction with administration of the hypertonic saline by a nebulizer. Patients were classified into neutrophilic (NA) or non-neutrophilic asthma (NNA) according to = 40 % or > 40 %, or <40% of neutrophils ratio in sputum. Characteristics of asthma sub-phenotypes were analyzed by disease severity, pulmonary function, blood eosinophil counts, total IgE levels in serum, and specific IgE antibody to environmental allergens.
Results: One hundred nineteen patients were divided into 54 NA or 65 NNA. There were no significant differences in the distribution of severity, FEV1 percent predicted, blood eosinophil counts and total IgE levels. In NA, 37 patients (68.5%) had specific IgE antibody to environmental allergens whereas 42 patients (64.6%) in NNA.
Conclusions: Proportion of patients with NA sensitized to environmental allergen was equal to NNA. Th2 immune response to aero-allergens might be contributed to development of neutrophilic inflammation in asthma.