IL-15 is an immunostimulatory cytokine sharing with IL-2 the IL-2Rβγ complex. In vivo, IL-15 detection in synovial fluids has been associated with the development of rheumatoid arthritis. A debate exists as to whether IL-15 has the potential to be secreted in meaningful amounts or to act as a pericellular cytokine. Our data show (1) the presence of two IL-15 isoforms displaying signal peptides of different length and the capacity to be secreted restricted to the isoform bearing the longer one; (2) in cells expressing the two isoforms, the existence of different nuclear localization and intracellular trafficking of IL-15 and IL-15Rα; and (3) an intercellular microcirculation of IL-15, not detectable with ELISA kits, but displaying a role as an anti-apoptotic factor able to induce the deflection of the TNFR associated factor 2 (TRAF) to IL-15Rα. Our data point to a juxtacrine mechanism of action of IL-15 and suggest a role for IL-15/IL-15Rα in the regulation of apoptosis.
|Number of pages||10|
|Journal||Annals of the New York Academy of Sciences|
|Publication status||Published - 1999|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)