INTERLEUKIN-15 SIGNALS T84 COLONIC EPITHELIAL-CELLS IN THE ABSENCE OFTHE INTERLEUKIN-2 RECEPTOR BETA-CHAIN

Interleukin-15 (IL-15) shares many biological functions with interleuk in-2 (IL-2) due to common receptor components. IL-15 binds to the IL-2 receptor (IL-BR) beta-chain and the common gamma-chain receptor in ad dition to one other IL-15 binding receptor protein (IL-15R alpha). Bot h IL-2R beta- and gamma-chains are required to promote cell growth in hematopoietic cells. The colonic cryptlike epithelial cell line T84 co ntains the common gamma-chain but lacks the IL-BR beta-chain. We repor t IL-15R alpha-chain mRNA in T84 cells with the use of reverse transcr iptase-polymerase chain reaction. T84 and normal colonic epithelial ce lls bind a FLAG-IL-15 fusion protein in immunoperoxidase and flow cyto metric experiments. In addition, IL-15, but not IL-2, accelerates and enhances the development of transepithelial resistance across T84 mono layers in a dose-dependent fashion. We conclude that normal and T84 co lonic epithelial cells express IL-15R alpha and are able to bind IL-15 . IL-15 can deliver a nonproliferative functional signal in the absenc e of IL-2R beta-chain in T84 cells.