T E Jessen1, L Ødum. 1. Department of Clinical Biochemistry, Holbaek, Sygehus Vestsjaelland, DK- 4300, Holaek, Denmark. chtoje@vestamt.dk
Abstract
OBJECTIVE: To investigate the role of tumor necrosis factor stimulated gene 6 (TSG-6) and metal ions in the coupling of inter-alpha-trypsin inhibitor (ITI) to hyaluronan in human synovial fluid. DESIGN: The concentration of ITI heavy chains bound to hyaluronan was determined by a two-step electrophoretic technique. Synovial fluid, TSG-6 depleted synovial fluid and metal chelated synovial fluid were tested for their ability to support the coupling of ITI heavy chains to hyaluronan. RESULTS: When synovial fluid was mixed with an ITI-source (serum or purified ITI), coupling of ITI heavy chains to hyaluronan took place. TSG-6 immunodepleated synovial fluid lost the coupling activity, but addition of recombinant TSG-6 restored the activity. EDTA inhibited the coupling activity, but combinations of the metal-ion chelators Mg-EGTA and Ca-EGTA demonstrated, that Ca++ is essential for the coupling of ITI heavy chains to hyaluronan. CONCLUSIONS: Tumor necrosis factor stimulated gene 6 (TSG-6) and calcium ions are both essential for the coupling of inter-alpha-trypsin inhibitor to hyaluronan in human synovial fluid.
OBJECTIVE: To investigate the role of tumor necrosis factor stimulated gene 6 (TSG-6) and metal ions in the coupling of inter-alpha-trypsin inhibitor (ITI) to hyaluronan in human synovial fluid. DESIGN: The concentration of ITI heavy chains bound to hyaluronan was determined by a two-step electrophoretic technique. Synovial fluid, TSG-6 depleted synovial fluid and metal chelated synovial fluid were tested for their ability to support the coupling of ITI heavy chains to hyaluronan. RESULTS: When synovial fluid was mixed with an ITI-source (serum or purified ITI), coupling of ITI heavy chains to hyaluronan took place. TSG-6 immunodepleated synovial fluid lost the coupling activity, but addition of recombinant TSG-6 restored the activity. EDTA inhibited the coupling activity, but combinations of the metal-ion chelators Mg-EGTA and Ca-EGTA demonstrated, that Ca++ is essential for the coupling of ITI heavy chains to hyaluronan. CONCLUSIONS:Tumor necrosis factor stimulated gene 6 (TSG-6) and calcium ions are both essential for the coupling of inter-alpha-trypsin inhibitor to hyaluronan in human synovial fluid.
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