EFFECTS OF DIFFERENT SECRETAGOGUES ON SYNOVIAL-FLUID MAST-CELLS FROM PATIENTS WITH RHEUMATOID-ARTHRITIS

Mast cells are considered to play a role in inflammatory joint diseases including rheumatoid arthritis. However, the in vivo secretagogues of these cells in rheumatoid arthritis have not yet been identified. Histamine secretions of 6.7%, 6.1%, 2.6% and 2.1% were observed for substance P, compound 48/80, bradykinin and calcitonin gene-related peptide, respectively. In contrast, A23187 and anti-IgE induced 48.6 +/- 3.8% and 25.0 +/- 6.7% histamine release. These effects were inhibited by zinc gluconate in a dose-dependent manner between 3 and 30-mu-M. Altogether these results show that human synovial fluid mast cells exhibit a low sensitivity to non-immunologic histamine releasers, possibly suggesting that only a small percentage of synovial fluid mast cells are sensitive to peptides.