Serum phospholipase A₂ enzyme activity and immunoreactivity in a prospective analysis of patients with septic shock

Massive elevations of serum phospholipase A₂ activity have been documented in patients with septic shock. Serum PLA₂ activity correlated to the degree and duration of circulatory collapse, while purified native PLA₂ reproduced hypotension in experimental animals. In a prospective study of patients with septic shock, we have determined the relationship of PLA₂ enzyme activity to PLA₂ immunoreactivity using radiolabelled E. coli phospholipid substrate and an ELISA specific for group II human nonpancreatic PLA₂. In all patients, there was a clear concordance of the two assays. Maximal PLA₂ concentration was increased a mean of 554-fold over normal levels. We found no evidence to support the presence of activating or inhibitory proteins. These data confirm that the observed increase in serum PLA₂ activity in septic shock is due to intravascular release of group II nonpancreatic PLA₂.