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

Abstract

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 μg/ml)-induced photon generation was abolished by an O₂^- scavenger, superoxide dismutase, and an H₂0₂ 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.