Differences between cytokine release from bronchial epithelial cells of asthmatic patients and non-asthmatic subjects: Effect of exposure to diesel exhaust particles

Background: Recent evidence suggests that the airways of asthmatics are mor e susceptible to adverse effects of air pollutants than the airways of non- asthmatics, but the underlying mechanisms are not clear. Methods: We have cultured bronchial epithelial cells (HBEC) from biopsies o f atopic mild asthmatic patients and nonatopic non-asthmatic subjects, and investigated constitutive and diesel exhaust particles (DEP)-induced releas e of several pro-inflammatory mediators. Results: HBEC of asthmatic patients constitutively released significantly g reater amounts of IL-8, GM-CSF and sICAM-1 than HBEC of non-asthmatic subje cts. RANTES was only released by HBEC of asthmatic patients. Incubation of the asthmatic cultures with 10 mu g/ml DEP significantly increased the rele ase of IL-8, GM-CSF and sICAM-1 after 24 h. In contrast, only the higher co ncentrations of 50-100 mu g/ml DEP significantly increased the release of I L-8 and GM-CSF from HBEC of non-asthmatics. Conclusions: These results suggest that the increased sensitivity of the ai rways of asthmatics to air pollutants such as DEP may, at least in part, be a consequence of greater constitutive and pollutant-induced release of spe cific pro-inflammatory mediators from their bronchial epithelial cells.