Bronchial interleukin-5 and eotaxin expression in nasal polyposis. Relationship with (a)symptomatic bronchial hyperresponsiveness.

Abstract

An eosinophilic bronchial inflammation was previously demonstrated in patients with nasal polyposis (NP) and asymptomatic bronchial hyperresponsiveness (BHR) similar to that observed in asthmatic patients with NP, whereas patients with NP without BHR did not. The aim of the study was to investigate the contribution of interleukin 5 (IL-5) and eotaxin to the pathogenesis of BHR associated with NP. Eleven patients with NP without BHR (Group A), 8 patients with NP and asymptomatic BHR (Group B), and 9 patients with NP and asthma (Group C) were included. Bronchial biopsies were studied for IL-5 and eotaxin immunoreactivity and IL-5 mRNA expression. IL-5 levels were determined in bronchial lavage (BL). Compared with Groups A and B, Group C patients exhibited higher numbers of IL-5 protein(+) cells, IL-5 mRNA(+) cells, and eotaxin(+) cells in bronchial submucosa. Compared with Group A, Group B patients showed an increased number of IL-5 protein(+) cells, whereas the number of IL-5 mRNA(+) cells and eotaxin(+) cells was similar. IL-5 levels in BL were increased only in Group C. Our study provides evidence of IL-5 involvement in bronchial eosinophilia and in the pathogenesis of asymptomatic BHR associated with NP, whereas both IL-5 and eotaxin are involved in asthma associated with NP.