The goal of this study was to examine the effect of alveolar epithelial cells on inflammatory responses in macrophages. Lung epithelial cells (either rat RLE-6TN or human A549 cells) reduced LPS-induced NO production in alveolar macrophages (AM) in a contact-independent mechanism. The inhibitory effect of the epithelial cells was present already at the transcriptional level: LPS-induced inducible NO synthase (iNOS) expression was significantly smaller. Surfactant protein A (SP-A)-induced NO production by alveolar macrophages was also reduced in the presence of A549 cells, though, by a different kinetics. LPS-induced interleukin-6 (IL-6) production (another inflammatory pathway) by alveolar macrophages was also reduced in the presence of RLE-6TN cells. These data suggest a role for lung epithelial cells in the complicated modulation of inflammatory processes, and provide an insight into the mechanism underlying.