Interleukin-8 (IL-8) is a neutrophilic chemotactic factor which may have a prominent role in the attraction of neutrophils to the lung in idiopathic pulmonary fibrosis (IPF). The objective of this study was to investigate the usefulness of IL-8 expression in bronchoalveolar lavage (BAL) cells in the evaluation of alveolitis in IPF. We analysed the BAL cell expression of IL-8 by immunocytochemistry in 19 patients with IPF (six smokers, three ex-smokers and ten non-smokers) and in a control group composed of 14 individuals (six smokers, eight non-smokers). In IPF, BAL was performed on both the pulmonary lobe with the most extensive involvement and the one less extensively involved on high-resolution computed tomography (HRCT) scans. The percentages and absolute numbers of BAL IL-8+ macrophages from lobes with the most extensive HRCT scan involvement (36 +/- 6% and (6 +/- 2 x 10(4) ml-1) (SE) and from those less extensively involved [26% +/- 4% and (6 +/- 1) x 10(4) ml-1] were significantly higher with respect to both those from healthy smokers [17% +/- 6% and (7 +/- 4) x 10(4) ml-1] and those from non-smokers [2% +/- 1% and (1 +/- 0.3) x 10(4) ml-1] (P = 0.005 and P = 0.001, respectively), without differences between the two lobes. In contrast, both the proportions and the absolute numbers of BAL neutrophils in IPF were significantly higher in lobes with the most extensively involved HRCT scan in comparison with lobes with the least extensive involvement [13% +/- 3%, (3 +/- 1) x 10(4) ml-1 vs. 8% +/- 2%, (1 +/- 0.3) x 10(4) ml-1, P = 0.05]. Moreover, the numbers of BAL neutrophils, but not those of IL-8+ macrophages, correlated with the extent of total pulmonary HRCT scan abnormalities in the most involved lobe (r = 0.64, P = 0.04). A correlation between neutrophils and IL-8+ cells was not observed. The results of this study suggest that, in IPF, BAL neutrophilia offers a better description of the disease inflammatory process than the expression of IL-8 in BAL cells.