An alkaline proteinase which has inflammatory activity isolated from guinea pig lymphoid cells

A phosphate buffer extract of regional lymph node cells (more than 90% lymphocytes) of guinea pigs immunized with bovine immunoglobulin G contained acid and alkaline proteinase activities. The immunized cells contained approximately twice as much proteinase activities than the normal cells. The alkaline proteinase was purified and two forms could be separated. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that one form labeled with [3H]diisopropylfluorophosphate was localized at Mr 28,000 in a single peak in the presence and absence of reducing agent. The enzyme was inhibited by diisopropylfluorophosphate, p-chloromercuribenzoate, N-ethylmaleimide and iodoacetic acid, and was also partially inhibited by phenylmethylsulfonyl fluoride. It was relatively heat-stable. Intradermal injection of the purified form into normal guinea pigs induced a mixed neutrophil-mononuclear infiltrate. The immune reaction was reduced in intensity with the diisopropylfluorophosphate-inhibited enzyme. These findings suggest that the proteinase probably participates in the inflammatory response of cellular hypersensitivity.