Phorbol 12-Myristate 13-Acetate (PMA)-Induced Oxyradical Production in Rheumatoid Synovial Cells

We successfully detected the oxyradical production in human synovial A (macrophage-like) and B (fibroblast-like) cells by phorbol 12-myristate 13-acetate (PMA) using the luminol-chemiluminescence method. The PMA (0.1 microgram/ml)-induced photon generation was abolished by an O2- scavenger, superoxide dismutase, and an H2O2 scavenger, catalase, suggesting that the stimulus produced oxyradicals in synovial cells. Both of these responses were abolished by a protein kinase C (PKC) inhibitor, calphostine C, but unaffected by an intracellular Ca2+ chelator, BAPTA-AM, and Ca2+ removal from the extracellular medium. These findings suggest that synovial A and B cells produce oxyradicals through PKC-mediated and [Ca2+]i-independent mechanisms, probably through the activation of NADPH oxidase.