Colony-stimulating factor-producing tumours: production of granulocyte colony-stimulating factor and interleukin-6 is secondary to interleukin-1 production.

We have reported that tumours producing colony-stimulating factor (CSF) also secrete interleukin-1 (IL-1) and IL-6. In the present study, we characterised the role played by IL-1 in CSF production. IL-1 receptor antagonist inhibited the production of granulocyte (G)-CSF and IL-6 by approximately 90% in CSF-producing human lung carcinoma cell lines. Similar results were obtained with hydrocortisone, which suppresses IL-1 gene expression. In contrast, 15 non-CSF-producing human lung carcinoma cell lines did not show detectable IL-1 production, although seven of them were induced to produce G-CSF and IL-6 by exogenous IL-1 alpha. Cell lines that responded to IL-1 alpha, including the CSF-producing lines, expressed receptors for IL-1 alpha. These results indicate that CSF-producing tumours can be characterised by their constitutive IL-1 production, IL-1 receptor expression and IL-1-dependent excess production of G-CSF and IL-6. Furthermore, transcription factor(s) may be involved in the abnormal IL-1 alpha production.