The significance of lysozyme (muramidase) in rheumatoid arthritis. i. levels in serum and synovial fluid

Abstract

Abstract Lysozyme (muramidase) * activity was estimated in 120 serum and 67 synovial fluid samples from patients with rheumatoid arthritis. These data were compared with the activity in samples from healthy controls and from patients with other forms of arthritis. In 35% of the serum samples and in 55% of the synovial fluid samples from patients with rheumatoid arthritis, lysozome activity was increased. Simultaneous estimations in serum and synovial fluid in 15 patients showed that lysozyme activity was significantly higher in synovial fluid than in serum. In serum from patients with other forms of arthritis, lysozyme activity was normal when renal function was normal. Low lysozyme levels were observed in synovial fluid obtained from patients with post‐traumatic arthritis, osteoarthritis, seronegative polyarthritis and arthritis associated with plasmacytic dyscrasias. However, high lysozyme levels were observed in acute gout, infectious arthritis and acute nonspecific synovitis. No direct correlation was found between the activity of lysozyme and the number of white blood cells in the synovial fluid. Attention is drawn here to the possible role of lysozyme as a contributor to intra‐articular inflammation.