Persistent polymorphonuclear neutrophil (PMN) recruitment to airway is thought to be an important component of continuing inflammation and progression of chronic destructive lung diseases. Although chemoattractants are required for the PMN to migrate, the nature of the chemoattractants in the airways has not yet been clarified. We therefore investigated the contribution of interleukin-8 (IL-8) and leukotriene-B4 (LTB4) to the chemotactic activity of lung secretions by inhibiting their activity using a monoclonal antibody to IL-8 and an LTB4 receptor antagonist (LY293111 sodium). Fifty-nine sputum samples obtained from 19 patients with bronchiectasis were studied. In preliminary studies the chemotactic responses to IL-8 and LTB4 were found to be additive, and we were able to remove their contribution independently with the appropriate antibody and antagonist. The chemotactic activity of the secretions was related to the macroscopic appearance (mucoid, mucopurulent, and purulent), and this appeared to be related to an increase in IL-8 contribution. Chemotactic activity was reduced by antibiotic therapy and again that seemed to relate to a reduction in the IL-8 contribution. The contributions of LTB4 were similar among the three types of sputum in varying clinical states. These data suggest that LTB4 and IL-8 are important chemotactic factors in lung secretions from such patients, although IL-8 appears to play a more important role during acute exacerbations. These results may be useful in determining therapeutic strategies for chronic destructive lung diseases in the future.

Previous work from the group has shown that non-steroidal anti-inflammatory agents given to volunteers and patients inhibit PMN function possibly by affecting the developing neutrophil during the differentiation process. In this study indomethacin treatment in vivo reduced neutrophil chemotaxis and proteolytic degradation of fibronectin, with a maximal effect after 14 days. Stimulated neutrophil adherence to fibronectin was also reduced but this was not due to quantitative changes in beta(2) integrin expression or function. L-Selectin expression on resting and stimulated neutrophils was increased after 14 days and there was a small decrease in plasma levels of soluble L-selectin. These effects, however, could not be reproduced by treatment of neutrophils with indomethacin in vitro, suggesting they are due to effects on differentiating/maturing PMNs. In an attempt to interpret these changes, studies were performed with dexamethasone, which is known to alter neutrophil function and kinetics. Dexamethasone treatment reduced chemotaxis and increased superoxide generation after 1 day and was associated with increased expression of activated beta(2) integrins and reduced L-selectin expression on resting neutrophils. This suggests the appearance of mainly 'activated' cells as a result of demargination and indicates that the effects of indomethacin are distinctive and not related to changes in compartmentalisation.

Neutrophils isolated from patients with chronic bronchitis and emphysema have been shown to have enhanced responses to formyl peptides when assessed in vitro compared to age, sex matched controls. It is currently unclear whether the observed differences are due to a 'priming' effect by a second agent in vivo, or whether this is a primary difference in the neutrophils. We have studied the effects of interleukin-8, which is thought to be one of the major pro-inflammatory cytokines in chronic lung disease and granulocyte macrophage colony stimulating factor (GMCSF), in order to assess their effects on neutrophil chemotaxis and connective tissue degradation. In addition, we have assessed the effect of preincubation of these agents with neutrophils for 30 min followed by stimulation with F-Met-Leu-Phe (FMLP) to investigate any possible 'priming' effect that may be relevant to our clinical data. We report suppression of neutrophil chemotaxis to FMLP following incubation of the neutrophils with both IL-8 and GMCSF. However, we have observed an additive effect of IL-8 and FMLP for neutrophil degranulation leading to fibronectin degradation. The results suggest that IL-8 does not 'prime' neutrophils for subsequent FMLP stimulation as observed in vivo. Although the results for GMCSF were similar for the chemotactic response, the agent also had a synergistic effect on connective tissue degradation. However, it is concluded that neither agent could explain the enhanced neutrophil responses seen in our patients.