RELEASE OF MAST-CELL MEDIATORS AND NITRITES INTO KNEE-JOINT FLUID IN OSTEOARTHRITIS - COMPARISON WITH ARTICULAR CHONDROCALCINOSIS AND RHEUMATOID-ARTHRITIS

In order to address the issue of the role of mast cells and nitric oxi de (NO) in joint effusions occurring in the course of osteoarthritis ( OA), synovial fluids collected from the knee of patients with OA, arti cular chondrocalcinosis and rheumatoid arthritis (RA) were studied for number of mast cells, and histamine, tryptase, phospholipase A2 and n itrite content. Mast cell counts are elevated in synovial fluid from O A patients when compared with RA. Histamine content in synovial fluid parallels the number of mast cells. Tryptase levels are elevated in OA in comparison with both other conditions, but do not reach the level of significance. Identical phospholipase A2 levels are recorded in thr ee groups. Nitrite concentrations are also higher in synovial fluid fr om OA patients when compared with RA patients. These results suggest t hat mast cells in association with various inflammatory cells, may con tribute to inflammation and cartilage breakdown in OA.