Abstract
Cathepsin G is one of serine proteases with chymotrypsin-like proteolytic activity and known to exist in neutrophils and spleens. We purified the protease from human bone marrow cells by extraction with 1 M potassium phosphate buffer (pH 7.0) and ap-plying to column chromatography of DEAF-cellulose, Sephadex G-100, CM-cellulose, and Mono-S. We further separated it into three isozymes by employing hydrophobic chromatography, and named them cathepsin.
Purified cathepsin G potentiated the effect of mitogens such as Con A and PHA on human lymphocytes. The protease further stimulated synthesis of both DNA and RNA of lymphocytes in the absence of mitogens. Effect of cathepsin G on the lymphocyte activity was prevented by inhibitors of cathepsin G. Therefore, the effect of it on lymphocyte activity is considered to be due to its proteolytic activity. The effect of cathepsin G on the function of lymphocytes differed among isozymes of the protease. From these results, we suppose that cathepsin G plays an important role in biophylaxis by regulating functions of lymphocytes.
