Proteolytic enzyme activities in rat peritoneal exudate

Proteinase activities in rat thioglycollate elicited peritoneal cells and the cell-free supernatant (lavage fluid) were measured by using the following substrates: Suc-Ala-Ala-Pro-Phe-Methyl-Coumarin-Amide (for Cathepsin G or chymase), Suc-Ala-Ala-Ala-AMC (for Elastase or elastase-like), Z-Arg-Arg-AMC (for Cathepsin B), haemoglobin (for Cathepsin D) and Ala-AMC (for alanine-aminopeptidase: AAP). The Enzyme activities were correlated to the quantitative distribution of various cell types in the exudate from 0 to 192 nd h. In the supernatant all the examined activities showed a higher value at 72nd h. In the cells activity of chymase and AAP proved to be very high at 0 h but after four h the activities were dropped. From this time all Enzyme activities started to elevate till the 24th h. At the 96th h only the activity of Cathepsin B and AAP had a high value. We conclude that the intracellular activation and secretion of proteolytic Enzymes characteristic for the various peritoneal cell types involved in the acute and chronic inflammatory reaction can be followed by activity measurements using enzyme-specific substrates and inhibitors.