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

An eosinophilic bronchial inflammation was previously demonstrated in patie nts with nasal polyposis (NP) and asymptomatic bronchial hyperresponsivenes s (BHR) similar to that observed in asthmatic patients with NP, whereas pat ients 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 p atients 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 an d eotaxin immunoreactivity and IL-5 mRNA expression. IL-5 levels were deter mined in bronchial lavage (BL). Compared with Groups A and B, Group C patie nts exhibited higher numbers of IL-5 protein(+) cells, IL-5 mRNA(+) cells, and eotaxin; cells in bronchial submucosa. Compared with Group A, Group B p atients showed an increased number of IL-5 protein cells, whereas the numbe r 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 involv ement in bronchial eosinophilia and in the pathogenesis of asymptomatic BHR associated with NP, whereas both IL-5 and eotaxin are involved in asthma a ssociated with NP.