LIPOPOLYSACCHARIDE-BINDING PROTEIN AS A MARKER OF INFLAMMATION IN SYNOVIAL-FLUID OF PATIENTS WITH ARTHRITIS - CORRELATION WITH INTERLEUKIN-6 AND C-REACTIVE PROTEIN

Objective. To determine levels of lipopolysaccharide binding protein ( LBP) in serum and in synovial fluid (SF) of patients presenting with v arious articular disorders [degenerative arthritis, rheumatoid arthrit is (RA), reactive arthritis (ReA)] and to correlate these levels with C-reactive protein (CRP) and interleukin 6 (IL-6), 2 markers of the ac ute phase response. Methods. LBP was measured by a radioimmunoassay ma de up of lipopolysaccharide (LPS) to capture LBP and radiolabelled ant i-LBP antibodies to detect LBP. LBP was also measured for its ability to present fluorescein isothiocyanate LPS (FITC-LPS) to human monocyte s, CRP was measured by nephelometry and IL-6 bioassay. Results. Levels of LBP in serum and in SF were significantly higher in patients with RA and ReA than in the control group of degenerative arthropathies. In the latter group, LBP values were similar to those found in controls. Serum LBP values correlated positively with SF LBP values. LBP values also correlated with CRP and IL-6 levels measured in SF. Functionally , LBP was found to be active and able to present LPS to monocytes, res ulting in tumor necrosis factor-alpha (TNF-alpha) release upon LPS cha llenge. Conclusion. These in vitro data support the observation that L BP could play a major role in local joint disorders. Our results also strengthen the view that LBP may be a new marker of synovial inflammat ion.