Dexamethasone and cyclosporin A do not inhibit interleukin-15 expression in the human lung carcinoma cell line A549.

A549 cells constitutively expressed IL-15 mRNA which could be upregulated by stimulation with TNF-alpha- or IL-1beta. Constitutive and induced levels of IL-15 mRNA were not decreased in the presence of 10- 6 M dexamethasone. Control experiments revealed that 10- 6 M dexamethasone inhibited the TNF-alpha- or IL-1beta-mediated increase of IL-8 mRNA in A549 cells, which showed that the glucocorticoid was functional. A549 cells did not secrete relevant amounts of IL-15 protein. The constitutive expression and the TNF-alpha- or IL-1beta-mediated upregulation of intracellular IL-15 protein was not inhibited by dexamethasone, in contrast, the release of IL-8 protein was inhibited. Also, cyclosporin A at 250 ng/ml did not inhibit the TNF-alpha-induced upregulation of IL-15 mRNA and intracellular IL-15 protein. The data suggest that the synthesis of IL-15 mRNA and protein is not influenced by immunosuppressive glucocorticoids or by cyclosporin A.