We have suggested that autocrine motility-like factor is expressed in rheumatoid synovial fluid (SF). We examined the biochemical features of the motile activity.
We investigated chemokinetic activities of SF from patients with osteoarthritis and joint trauma as well as rheumatoid arthritis (RA) using a unique protein-free culture fibrosarcoma system. We then investigated biochemical features and the signal transduction pathway of the motile activity expressed in RA.
We found chemokinetic activity in SF from all patients. However, ability to block binding of the monoclonal antibody to the receptor for autocrine motility factor (AMF) was observed only in rheumatoid SF on immunoblots. Biochemical investigation indicated motile activity to be heat labile, trypsin sensitive, and eluted at high salt concentration from an anion exchange column. Stimulated motility of rheumatoid SF was inhibited by the pertussis toxin, staurosporine (C kinase inhibitor), and genistein (tyrosine kinase inhibitor), but not by A kinase inhibitor, H-8.
The cell motility activity expressed in rheumatoid SF appears to be AMF, and the cytokine may be essential for communication among leukocytes in rheumatic disease.