CHARACTERIZATION OF PHOSPHOLIPASE-A(2) FROM HUMAN NASAL LAVAGE

A secreted form of phospholipase A2 (PLA2) has been implicated in infl ammatory disorders such as rheumatoid arthritis and sepsis. To determi ne if PLA2 may also play a role in allergic rhinitis, we have measured enzymic activity in nasal lavage from allergic subjects. Enhanced act ivity of PLA2 in the lavage was observed following nasal challenge wit h antigen or histamine. The PLA2 in the nasal lavage was partially pur ified by acid extraction, size exclusion chromatography, and ion excha nge chromatography. The partially purified enzyme from nasal lavage wa s subsequently compared to a recombinant form of human PLA2 identified in synovial fluid from arthritic patients. The two enzymes showed sim ilar molecular weights (15 to 16 kD) on SDS-PAGE, and both reacted wit h a rabbit polyclonal antiserum raised to a galactokinase-PLA2 fusion protein. The enzymatic activities of the two PLA2s were indistinguisha ble when compared for ionic dependence, substrate selectivity, and sen sitivity to inhibitors. These results suggest that the PLA2 induced in nasal lavage in response to challenge by antigen is very similar to t he extracellular PLA2 found in synovial fluid from subjects with rheum atoid arthritis and may play a role in the inflammatory processes asso ciated with allergic rhinitis.