Cellular origin of cathepsin B in carrageenin-induced granuloma tissues in rats

Cathepsin B isolated from carrageenin-induced granuloma tissue was separated into two peaks (one large and one small) on CM-cellulose column chromatography. The cathepsin B activities from the peritoneal macrophages and polymorphonuclear leukocytes were eluted at the positions identical to those of the larger (P-D and the smaller (P-II) peaks, respectively. Similarly, the cathepsin B activities in the P-I and P-II fractions from granuloma tissue corresponded to those from macrophages and leukocytes, respectively, in isoelectric focusing in polyacrylamide gel. Both the cathepsin B activities were completely inhibited by iodoacetamide and leupeptin, but phenylmethanesulfonyl fluoride and o-phenanthroline were ineffective. The molecular weight of the cathepsin B of the cellular origin and granuloma tissue was approximately 24,000 by gel filtration. The pI value of cathepsin B in the P-I and P-II fractions from granuloma tissue was 5.09 and 5.18, respectively. These results strongly suggest that two types of cathepsin B in granuloma tissue may be different in cellular origin and may be isozymes.