[Effect of Bac. intermedius RNAse on a cell population of ascitic lympholeukemia NKLy]

RNAase of Bac. intermedius and a modification of this enzyme containing a histidine-inactivated active site were studied for their influence on the activity of proliferation of murine ascitic lympholeukemia cells (NKLy) using a 3H thymidine label. Each mouse received a single intraperitoneal injection (dosage 1 mg per kg) of the normal or inactivated enzyme. It was shown that irrespective of the catalytic activity both enzyme preparations decreased the proliferative activity of the cells, blocked G2-M, slowed the course of the prophase and metaphase of meiosis, diminished the number of cells synthetizing DNA and lowered the intensity of labelling. After 24 hours all these characteristics returned to normal.