The involvement of CD44 and its novel ligand galectin-8 in apoptotic regulation of autoimmune inflammation

Lora Eshkar Sebban, Denise Ronen, David Levartovsky, Ori Elkayam, Dan Caspi, Suhail Aamar, Howard Amital, Alan Rubinow, Ira Golan, David Naor*, Yehiel Zick, Itshak Golan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The synovial fluid (SF) cells of rheumatoid arthritis (RA) patients express a specific CD44 variant designated CD44vRA. Using a cellular model of this autoimmune disease, we show in this study that the mammalian lectin, galectin-8 (gal-8), is a novel high-affinity ligand of CD44vRA. By affinity chromatography, flow cytometry, and surface plasmon resonance, we demonstrate that gal-8 interacts with a high affinity (Kd, 6 × 10-9 M) with CD44vRA. We further demonstrate that SF cells from RA patients express and secrete gal-8, to a concentration of 25-65 nM, well within the concentration of gal-8 required to induce apoptosis of SF cells. We further show that not all gal-8 remains freely soluble in the SF and at least part forms triple complexes with CD44 and fibrinogen that can be detected, after fibrinogen immunoprecipitation, with Abs against fibrinogen, gal-8 and CD44. These triple complexes may therefore increase the inflammatory reaction by sequestering the soluble gal-8, thereby reducing its ability to induce apoptosis in the inflammatory cells. Our findings not only shed light on the receptor-ligand relationships between CD44 and gal-8, but also underline the biological significance of these interactions, which may affect the extent of the autoimmune inflammatory response in the SF of RA patients.

Original languageEnglish
Pages (from-to)1225-1235
Number of pages11
JournalJournal of Immunology
Issue number2
StatePublished - 15 Jul 2007
Externally publishedYes


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