Immunohistochemical localization of phospholipase A2 in human pancreas in acute and chronic pancreatitis.

Phospholipase A2 was localized with peroxidase anti-peroxidase (PAP)-technique in pancreatic tissue resected from normal portions of tumor-bearing glands of 4 patients and from pancreases of 16 patients suffering from either acute or chronic pancreatitis. In acute pancreatitis the enzyme immunoreactivity was detected in the apical zymogen granule portion of acinar cells and in ductal secretory material similarly as in normal tissue. At the border of necrotic and non-necrotic exocrine parenchyma the staining reaction was evenly dispersed throughout the cytoplasm or localized in small cell fragments. There was no reaction in necrotic acinar cell remnants. Some dilated acinar lumina contained intensively stained plugs. Fat necroses were stained but surrounding neutrophil leukocytes were unstained. Thrombosed small vessels were also unstained. In chronic pancreatitis, diminished staining characterized small acinar cells at the border of lobules. Some macrophages stained positively. It was concluded that during acute inflammation in pancreas, localization of phospholipase A2 in pancreatic tissue is abnormal, and that phospholipases A2 of neutrophil leukocytes and platelets are not crossreactive with the secretory enzyme.