Proteinase activity and agglutination of leukemia cells.

The proteinase activity was assayed in the leukemia cells L 1210 and in the ascites fluid with [3H] acetylated haemoglobin as a substrate. The proteinase activity at pH 4.1 increased in cells and in the ascites fluid with age of the tumor. The proteinase activity at pH 7.8 was low, but the enzyme activity in the cell homogenate increased between 5th and 7th day of the tumor growth and it was also present in the ascites fluid. It was observed that the leukemia cells aggregate in vivo and in vitro at pH values of the ascites fluid above pH 7.0. It was suggested, that the aggregation of leukemia cells is due to the tumor cell proteinase activity released to the ascites fluid.