[Peculiarities of induced sputum inflammatory cell counts in allergic versus non-allergic asthma]

According to the Global Initiative for Asthma (GINA, updated 2004), although non-allergic asthma has a different clinical profile than allergic asthma, it is not a distinct immunopathological entity. We aimed to investigate the peculiarities of inflammatory cell counts in induced sputum from patients with allergic and non-allergic asthma.

We investigated 41 steroid naive patients (mean age 51.8+/-1.5 years) with mild persistent asthma. Depending on the results of allergic anamnesis and skin prick test, patients were divided into the two groups: 21-with allergic asthma, 20-with non-allergic asthma. Spirometry, bronchial provocation test with methacholine (PD20) and sputum induction with hypertonic saline were performed. Cytospins of induced sputum were stained with May-Grunwald-Giemsa for differential cell counts. RESULTS. In samples from non-allergic asthmatics we detected a significantly higher number of total cells (1.97+/-0.33 vs 1.23+/-0.11x10(6)/ml, p<0.01), neutrophils (1.34+/-0.18 vs 0.41+/-0.06x10(6)/ml, p<0.01) and lymphocytes (0.36+/-0.04 vs 0.15+/-0.03x10(6)/ml, p<0.01), than in samples from allergic asthmatics. Number of eosinophils and macrophages did not significantly differ between two groups. In non-allergic asthmatics, number of lymphocytes correlated with PD20 (Rs=0.41, p<0.05); in allergic asthmatics, number of eosinophils in induced sputum correlated with PD20 (Rs=0.71, p<0.05).

Our data suggest that lymphocytes might play a more important role in pathogenesis of non-allergic asthma, while eosinophils -- in allergic asthma.