The activities of plasma-membrane marker enzymes in rheumatoid synovial tissues and fluids.

The activities of 5'-nucleotidase, K+, Na+-activated Mg2+-dependent adenosine triphosphatase (ATPase) and leucine-beta-naphthylamidase were determined from 17 rheumatoid synovial fluids and from extracts of the corresponding synovial tissues. There was little correlation between the enzyme activities in the synovial fluids and those in the respective synovial-tissue extracts. In seropositive cases of rheumatoid arthritis the activities of 5'-nucleotidase and leucine-beta-naphthylamidase in the synovial-tissue extract were higher than in seronegative cases. Also, the ratios of the enzyme activities in the synovial fluids to the resepctive activities in synovial tissue were lower in the seropositive cases. The activity of 5'-nucleotidase in the synovial tissue decreased during gold treatment.