A role in tumor progression has been proposed for transforming growth factor-beta 1 (TGF beta 1) and interleukin (IL)-8 as well as for IL-1, which itself induces the production of TGF beta 1 and IL-8 in many cell types. TGF beta 1 and IL-8 production and their regulation by IL-1 in five non-small-cell (NSC) lung tumor cell lines were evaluated. Moreover, their levels were evaluated in 29 NSC lung tumors. All cell lines constitutively produced TGF beta 1, and three produced IL-8. After IL-1 beta treatment, TGF beta 1 production was upregulated in two cell lines, whereas IL-8 production was markedly upregulated in two, induced in one, and unmodified in two. In tumors, the levels of TGF beta 1, IL-8, and IL-1 beta were higher than in normal counterparts (p < 0.001), and a positive correlation between IL-8 and IL-1 beta levels (p < 0.001) was found. TGF beta 1, IL-8, and IL-1 beta mRNA expression was examined in 12 tumors. TGF beta 1 mRNA was detected in all cases, IL-8 mRNA in 7, and IL-1 beta MRNA was undetectable. TGF beta 1, IL-8, and IL-1 beta immunoreactivity was then studied by immunohistochemistry. TGF beta 1 and IL-8 immunoreactivity was observed in neoplastic cells; IL-1 beta immunoreactivity was observed in mononuclear cells. In conclusion, in tumors IL-1 beta levels positively correlated with those of IL-8, and IL-1 beta as well as TGF beta 1 and IL-8 levels were significantly higher than in normal tissues.