Serum pancreatic phospholipase A2 and prophospholipase A2 in acute pancreatitis and after endoscopic retrograde pancreatography.

Serum immunoreactive pancreatic phospholipase A2 (IP-PLA2) levels and the proportion of active pancreatic PLA2 in the serum IP-PLA2 were determined by radioimmunoassay with an antibody directed against active human PLA2. The subjects of this study included eight patients who underwent endoscopic retrograde pancreatography (ERP), nine patients with acute pancreatitis, and six healthy controls. The serum IP-PLA2 levels were elevated after ERP and during acute pancreatitis. The amount of active pancreatic PLA2 in the serum was determined after its separation from pancreatic prophospholipase A2 using reverse-phase high-performance liquid chromatography (HPLC). The serum IP-PLA2 was separated into two peaks on reverse-phase HPLC. The one which eluted faster contained the PLA2 activity; the other peak did not. The latter IP-PLA2 peak consisted of pancreatic prophospholipase A2 as judged by HPLC analysis and PLA2 activity determination of the products after treatment with trypsin. The proportion of active pancreatic PLA2 in the serum IP-PLA2 of patients after ERP (13.9 +/- 0.5%) increased slightly compared with that in fasting, healthy controls (8.0 +/- 1.1%). For those with acute pancreatitis, the proportion of active pancreatic PLA2 within 48 hours of hospital admission increased more markedly (44.0 +/- 5.7%) than that after ERP. These findings demonstrate that the proportion of active pancreatic PLA2 in the serum IP-PLA2 markedly increases during the early stage of acute pancreatitis, and that an ERP-induced rise in the intraductal pressure leads to the leakage of pancreatic PLA2 into the circulation, but not to a marked activation of the leaked enzyme.