PROTEOLYTIC-ENZYMES IN HUMAN LEUKEMIC LYMPHOID-CELLS .2. COMPARATIVE CHARACTERIZATION OF PROTEOLYTIC-ENZYMES AND THEIR INHIBITORS IN 3 TYPES OF LYMPHOID-CELLS

A comparative study of proteolytic enzymes and their inhibitors in thr ee human leukemic lymphoid cell populations has been carried out. Aspa rtate and cysteine proteinases (cathepsins B, L, H), serine trypsin-li ke proteinases, aminopeptidases, dipeptidyl aminopeptidase IV (DAP IV) , and urokinase type plasminogen activator (uPA) were detected in lysa tes of the investigated cells whose phenotypes corresponded to mature B-lymphocytes, T-helpers, and T-cells at earlier stages of differentia tion. The activities of individual proteinases and their ratios in lys ates of different cells varied significantly, attesting to a different array of proteolytic enzymes in different lymphoid cells. HPLC studie s of lysates revealed the presence of inhibitors of cysteine and serin e trypsin-like proteinases along with the aforementioned enzymes. A pr ocedure for simultaneous isolation of aspartate proteinases (cathepsin D), cysteine proteinases, and their inhibitors from leukemic B-cells has been developed Partially purified preparations of cathepsins B and L and their inhibitors were isolated and some of their properties inv estigated.