Cloning and Recombinant Expression of Phospholipase A2 Present in Rheumatoid Arthritic Synovial Fluid

Synovial fluid from arthritic patients contains multiple forms of phospholipase A2 (PLA2), as resolved by high performance liquid chromatography (Seilhamer, J.J., Plant, S., Pruzanski, W., Schilling, J., Stefanski, E., Vadas, P., and Johnson, L. K. (1989) J. Biochem. (Tokyo), submitted for publication). Here we describe the cloning of a human 4.5-kilobase gene and 800-base pair cDNA encoding the form representing the major peak of activity and protein mass (peak A). The clones encode a mature peptide of 124 amino acids, which follows a prepeptide of 20 residues. The deduced amino acid sequence constitutes an enzyme of the "Type II" class of PLA2s, and resembles PLA2s from other mammalian sources. This represents the first report of a full length mammalian non-pancreatic PLA2 sequence. Active transcription of this PLA2 gene was detected in two different inflammatory cell sources. Recombinant human peak A PLA2 was expressed in vaccinia as a secreted protein which accumulated in conditioned medium.