Distribution of pancreatic (group I) and synovial-type (group II) phospholipases A2 in human tissues

The catalytic activity of phospholipase A2 (cat-PLA2) and the concentration of pancreatic (group I) phospholipase A2 (pan-PLA2) and synovial-type (group II) phospholipase A2 (syn-PLA2) were studied in 19 human tissues in order to find potential sources of circulating phospholipase A2. Five specimens of each tissue were collected at autopsies or from normal deliveries (placentas and amnionic membranes). The concentrations of pan-PLA2 and syn-PLA2 were measured by specific time-resolved fluoroimmunoassays. The cat-PLA2 was measured by radioactive dipalmitoyl phosphatidylcholine as substrate. The concentration of pan-PLA2 was negligible in all tissue homogenates except the pancreas. Immunoreactive syn-PLA2 was found in the homogenates of the digestive tract, cartilage, and prostatic and parotid glands. By immunohistochemistry, syn-PLA2 was localized in Paneth cell secretory granules, chondrocytes, cartilage matrix, and glandular cells of prostate.