Immunoreactive Pancreatic Phospholipase A2 Research Articles

Phospholipase A2 in Sodium Taurocholate-Induced Experimental Hemorrhagic Pancreatitis in the Rat

We investigated the concentration of immunoreactive pancreatic phospholipase A2 (pan-PLA2) and the catalytic activity of phospholipase A2 (CA-PLA2) in plasma, peritoneal fluid, and pancreas of rats in which acute hemorrhagic pancreatitis was induced by an intraductal injection of sodium taurocholate. The contribution of pancreas to the CA-PLA2 in plasma was studied by removing pancreatic PLA2 by absorbing plasma samples with a polyclonal antibody raised in a rabbit against rat pancreatic PLA2. Sodium taurocholate injected into the pancreatic duct produced hemorrhagic pancreatitis with necrosis and inflammatory cell invasion within 8 hr. Saline injection caused edematous pancreatitis, but sham operation did not alter pancreatic morphology from normal. The concentration of pan-PLA2 increased rapidly in plasma in all animals, but significantly more in sodium taurocholate-injected animals than in saline-injected or sham-operated animals. The level of CA-PLA2 in plasma increased in sodium taurocholate-injected animals only. There was no correlation between pan-PLA2 and CA-PLA2 values in plasma in sodium taurocholate-injected animals. The CA-PLA2 was marginally increased in pancreatic tissue of sodium taurocholate-injected animals compared to that of saline-injected and sham-operated animals at 8 hr. Treatment by the anti-pan-PLA2 antibody effectively removed pan-PLA2 from plasma and peritoneal fluid samples in sodium taurocholate-injected animals. The level of CA-PLA2 in plasma was similar before and after antibody treatment. It was concluded that the concentrations of pancreatic PLA2 and the catalytic activity of PLA2 increase in rat plasma during experimental hemorrhagic acute pancreatitis. The catalytically active PLA2 in plasma is derived from a nonpancreatic source(s).

Pancreatic phospholipase A2 in cerulein-induced acute pancreatitis in the rat

We investigated the concentration of immunoreactive pancreatic phospholipase A2 (pan-PLA2) and the catalytic activity of phospholipase A2 (CA-PLA2) in plasma and pancreases of rats with cerulein-induced acute pancreatitis. Edematous pancreatitis with ascites and fat necroses in the abdominal cavity developed after 8 h infusion of cerulein (5 micrograms/kg/h). Large vacuoles were found in acinar cells and there were small areas of acinar cell necrosis. No pathological changes were seen in saline-infused control animals. Pancreatic PLA2 was localized by immunohistochemistry in pancreatic acinar cells in both groups of animals and in the proximal tubular cells of the kidney in cerulein-infused animals. The lungs and kidneys appeared normal by light microscopy in all animals. The pan-PLA2 values increased markedly, whereas the CA-PLA2 values did not change during the cerulein-infusion. The CA-PLA2 values in the homogenates of pancreatic tissue of cerulein-infused animals did not differ significantly from those of saline-infused controls. The results indicate that the CA-PLA2 in plasma is independent from the concentration of pan-PLA2 in cerulein-induced acute pancreatitis in rat.

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.

Clinical significance of serum immunoreactive pancreatic phospholipase A2(PLA2) assay in liver diseases

Serum pancreatic PLA2 levels were measured in 140 patients with miscellaneous liver diseases and 20 healthy adults by the method of radioimmunoassay using a monoclonal antibody to type I (pancreatic) PLA2. Serum pancreatic PLA2 levels in fulminant hepatitis were significantly higher than those in healthy controls and all other liver disease groups. Serum pancreatic PLA2 showed positive correlations with total and direct bilirubins, BUN and creatinine (P<0.001), amylase, lipase and thrombomodulin (P<0.01), and negative correlations with cholesterol (P<0.01), total protein and bilirubin (P<0.05), but no correlation with aminotransferases, biliary enzymes, Ch-Ease, endothelin-1 and KICG. For serum pancreatic PLA2 elevation in liver diseases, a complicating renal damage, pancreatic damage as a part of multiple organ failure, and liver failure through a vascular endothelial damage must be considered.

The diagnostic value of serum pancreatic phospholipase A2 (PLA2) in pancreatic diseases

The diagnostic significance of serum immunoreactive pancreatic phospholipase A2 (PLA2) was studied in 119 patients with pancreatic disease, 200 with various non-pancreatic disease, and 203 healthy controls using radioimmunoassay (RIA) specific to human pancreatic PLA2. This newly developed RIA using monoclonal antibody was satisfactorily sensitive and reliable. Serum PLA2 was elevated in all six patients with acute pancreatitis. Frequency of abnormal serum PLA2 levels was 60% in chronic pancreatitis (n = 52) and 67% in pancreatic cancer (n = 61). Serum PLA2 levels were low in chronic pancreatitis with severe exocrine insufficiency and advanced pancreatic cancer. In chronic pancreatitis, patients with low serum PLA2 level showed lower enzyme output in secretin test than patients with normal or high serum PLA2 level. Frequency of abnormal PLA2 levels was 27% in non-pancreatic disease and, in particular, patients with renal failure showed high PLA2 levels. Sensitivity (62%) and efficiency (69%) of serum PLA2 assay in pancreatic disease were superior to those of amylase. In conclusion, serum PLA2 determination using RIA was useful for the diagnosis of acute pancreatitis by high serum PLA2 levels and the diagnosis of severe exocrine pancreatic insufficiency by low serum PLA2 levels.

Serum Immunoreactive Pancreatic Phospholipase A2 in Patients with Various Malignant Tumors

The high incidence (40.6%) of elevated serum pancreatic phospholipase A2 (PLA2) was demonstrated in patients with various malignancies. Serum PLA2 was significantly increased in cancer patients compared with healthy sex- and age-matched blood donors (358.4 +/- 168.0 vs. 241.7 +/- 69.0 ng/dl; p less than 0.01). No correlation was observed between serum PLA2 and carcinoembryonic antigen (CEA) in these patients. Although patients with advanced and distantly metastatic cancer of the liver, gallbladder and pancreas showed higher PLA2 levels in serum than those with early cancer, patients with other cancers showed no correlation between serum PLA2 and clinical stage. A combined assay of PLA2 and CEA increased the sensitivity of detection of cancers to 60.8%.

The role of phospholipase A2 in human acute pancreatitis.

Several studies suggest that the activation of pancreatic phospholipase A2 (PLA2) and its release from injured acinar cells play an important role in the pathogenesis of acute pancreatitis. Elevated catalytic activity of PLA2 in serum is associated especially with severe forms of the disease. PLA2 has been purified from human cadaver pancreas and an antiserum raised against the enzyme in rabbits. Immuno-histochemical localization of PLA2 in pancreatic tissue was abnormal in acute pancreatitis. A time-resolved fluoroimmunoassay for human pancreatic PLA2 has been developed. Increased serum concentrations of immunoreactive PLA2 were found in acute pancreatitis during the first week after hospital admission. The values returned to normal somewhat more slowly than corresponding serum amylase values. The immunochemical determination of PLA2 in serum provides a fast and specific detection of injury to pancreatic acinar cells. The pancreas is not the only source of PLA2 in acute pancreatitis. The nonpancreatic PLA2 may originate from various inflammatory cells, but this hypothesis remains to be proven.

Immunoreactive pancreatic phospholipase A2 and catalytically active phospholipases A2 in serum from patients with acute pancreatitis.

Measuring the content of immunoreactive pancreatic phospholipase A2 (PLA2; EC 3.1.1.4) and the catalytic activity of PLA2 in serum samples from five patients with acute pancreatitis, we found no correlation between these two measurements overall. To test the specificity of the method for catalytic PLA2, we measured PLA2 activity in serum samples before and after immunoadsorption with an antiserum to human pancreatic PLA2. The results suggest the presence of at least two immunologically distinct PLA2 enzyme proteins in sera from these patients. One of the enzymes is pancreatic in origin and may exist in active, inactive, or inhibited form. The activity profile of the second PLA2 enzyme in serum during acute pancreatitis differs from that for other common pancreatic enzymes. In the present experiment, the catalytic activity was not removed by treatment with the anti-human pancreatic PLA2 antiserum. The source of this second PLA2 activity is unknown. Some samples contained increased activities of both PLA2 forms.