Expression of adhesion molecules on synovial fluid and peripheral blood monocytes in patients with inflammatory joint disease and osteoarthritis

Objective-To determine the presence of adhesion molecules on monocytes/macr ophages (M phi) from peripheral blood (PB) and synovial fluid (SF) in patie nts with osteoarthritis (OA) and inflammatory joint diseases (rheumatoid (R A) and reactive arthritis (ReA)) in order to improve our understanding of t he possible mechanisms underlying the inflammatory process. Methods-Whole blood and SF cells were stained with monoclonal antibodies ag ainst CD11a (LFA-1), CD15 s (sialyl-Lewis X), CD44, CD54, VLA-4, and HLA-DR counterstained with anti-CD14 antibodies as a M phi marker for dual fluore scence analysis by flowcytometry. Results-On PB-M phi, CD15s was markedly increased in both RA as well as ReA compared with OA. Furthermore, in the PB LFA-1, CD44, and HLA-DR showed a higher surface density on M phi in ReA than in OA. Comparison between SF an d PB showed significantly higher CD44 and CD54 expression on SF-M phi; Thes e molecules play an important part in lymphocyte-M phi interaction. Conclusion-In PB from patients with inflammatory joint diseases, M phi are activated, allowing recruitment into the synovial compartment. These disord ers, in contrast with OA seem to be "systemic" in nature. Within the SF, di fferent adhesion molecules are expressed on CD14(+) M phi as compared with PB.