A method of inhibiting the secretion of IL-8 and other pro-inflammatory cytokines from cells secreting elevated levels of these compounds is provided. The method includes contacting the cell with a composition comprising a cardiac glycoside such as oleandrin. The cardiac glycoside can be used to treat cystic fibrosis and other IL-8 dependent disorders by lowering levels of spontaneously secreted IL-8 and other pro-inflammatory cytokines. Oleandrin was found to suppress the secretion of IL-8 from cultured CF lung epithelial cells in the nanomolar concentration range. Structure-activity relationships (SARs) for cardiac glycosides are also elucidated.
