[Comparative characteristics of lymphocyte proteolytic enzymes in normal conditions and in chronic lymphoid leukemia]

Abstract

Proteolytic activity was estimated in lymphocyte lysates of cattle in normal state and in chronic lympholeukosis using 3H-acetylated casein (pH 7.4) and 3H-acetylated hemoglobin (pH 4.0) as substrates. Distinct individual variations in the enzymatic activity were observed either in neutral or slightly-acid media in the animal groups studied. In chronic lympholeukosis specific proteolytic activity, calculated per a cell, was decreased, while it was increased in calculation per a mg of protein. The lower content of protein (about 2.4-fold) was found in lysates of lymphocytes in chronic lympholeukosis as compared with normal state. An increase in proteolytic activity in lymphocyte lysates correlated with elevation of blood leukocytosis if chronic lympholeukosis developed in individual animals. Effects of a number of proteinase inhibitors and activators were studied in the cell lysates; the spectrum of proteinases in chronic lympholeukosis was dissimilar to that of normal state. Pepstatin inhibited quite completely the proteolytic activity at pH 4.0 in lymphocytes of healthy animals and hence cathepsin D was responsible for the activity; in chronic lympholeukosis, except of cathepsin D, thiol-dependent proteinase was also detected. Activity of proteinases at neutral pH value in lymphocytes of healthy and impaired animals was inhibited by phenylmethionine fluorosulfate and p-chloromercuribenzoate, thus suggesting that serine and thiol-dependent proteinases were present; the level of these enzymes was distinctly higher in chronic lympholeukosis as compared with normal state.