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Arthritis
Volume 2012 (2012), Article ID 943156, 7 pages
http://dx.doi.org/10.1155/2012/943156
Research Article

Proinflammatory Soluble Interleukin-15 Receptor Alpha Is Increased in Rheumatoid Arthritis

1Pharmaceutical Division, Center for Genetic Engineering and Biotechnology, 10600 Havana, Cuba
2Rheumatology Department, H. Ameijeiras Hospital, San Lazaro 701, 10300 Havana, Cuba

Received 20 February 2012; Revised 17 April 2012; Accepted 25 May 2012

Academic Editor: Adriana Rojas-Villarraga

Copyright © 2012 Ana Cecilia Machado Diaz et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Rheumatoid arthritis (RA) is an autoimmune and inflammatory disease in which many cytokines have been implicated. In particular, IL-15 is a cytokine involved in the inflammatory processes and bone loss. The aim of this study was to investigate the existence in synovial fluid of soluble IL-15Rα, a private receptor subunit for IL-15 which may act as an enhancer of IL-15-induced proinflammatory cytokines. Soluble IL-15Rα was quantified by a newly developed enzyme-linked immunosorbent assay (ELISA) in samples of synovial fluid from patients with RA and osteoarthritis (OA). The levels of IL-15Rα were significantly increased in RA patients compared to OA patients. Also, we studied the presence of membrane-bound IL-15 in cells from synovial fluids, another element necessary to induce pro-inflammatory cytokines through reverse signaling. Interestingly, we found high levels of IL-6 related to high levels of IL-15Rα in RA but not in OA. Thus, our results evidenced presence of IL-15Rα in synovial fluids and suggested that its pro-inflammatory effect could be related to induction of IL-6.