Inhalation exposure to ozone (O3) is known to induce epithelial and inflammatory changes in the lungs, characterized by neutrophilia and changes in epithelial permeability. Several cell types and their soluble mediators, including interleukin-1 (IL-1) and tumor necrosis factor- (TNF- ), are involved in the evolution of these responses. In this study, we have compared the effects of the combination of anti-IL-1 and anti-TNF- on in vitro and in vivo responses to inhaled O3. Male, Sprague-Dawley rats were exposed, nose-only, to 0.8 ppm O3 for 3 h and the in vitro and in vivo parameters were measured 8-12 h following exposure. The in vitro studies revealed that the adherence of inflammatory cells, primarily macrophages, harvested from the lungs of O3-exposed rats to cultured lung epithelial cells (ARL-14) was significantly greater than the adherence of macrophages from air-exposed controls. Furthermore, this adherence was significantly reduced in antibodytreated cells as compared to cells treated with preimmune rabbit serum. In vivo, elevations were found in the percentage of neutrophils in bronchoalveolar lavage fluid (BALF), 99m transport of Tc-diethylenetriaminepentaacetate (DTPA) across the tracheal epithelium, and concentrations of total protein and albumin in BALF following O3 exposure. However, these effects were not significantly altered by treatment with the anti-IL-1 /anti-TNFcombination. Therefore, it was concluded that O3 affects the early stages of the inflammatory response, particularly with respect to macrophage activation and adherence to epithelial cells, and that this early response may be mediated by IL-1 and/or TNF- . The results also suggest that the in vivo effects of O3 are controlled by complex mechanisms involving factors other than IL-1 and TNF- , even though these cytokines are capable of modifying macrophage function as revealed by the in vitro adherence studies.