Membrane-associated phospholipase A2 detected by a radioimmunoassay is a sensitive marker of inflammation in rheumatoid arthritis.

To investigate the clinical significance of membrane-associated phospholipase A2 (M-PLA2) measured by a radioimmunoassay(RIA) in rheumatoid arthritis, we examined serum M-PLA2 concentrations in 16 patients with rheumatoid arthritis. All showed elevated levels of serum M-PLA2. On the other hand, serum concentrations of C-reactive protein (CRP) and IL-6 were increased in 13 (81.3%) and 14 (87.5%) of 16 patients, respectively. The serum concentrations of M-PLA2 were significantly correlated with those of CRP. These results indicate that M-PLA2 is an acute phase reactant and a sensitive and useful marker of inflammation in rheumatoid arthritis.