Collagenolytic activity in the human leukemic K-562 cell line before and after induction of erythroid differentiation

K-562 cells were studied for their ability to produce collagenolytic enzymes in culture. Collagenolytic activity has been assayed by a fluorescamine method, it requires Ca2+ ions and is optimal at pH 7.5. It is present within the cells in the cytoplasm and bound to membranes, in addition it is excreted into the medium. Cellular collagenolytic activity is activated by trypsin and inhibited by cysteine and serum. Total cellular activity of K-562 cells corresponds to 30 and 60% of that found respectively in human granulocytes and promyelocytic human HL 60 cells. Induction by hemin of erythroid differentiation in K-562 cells leads to a reversible decrease in collagenolytic activity which is concomitant with the recruitment of hemoglobin-synthesizing cells. The use of spontaneously low and highly hemoglobinized clones of K-562 cells confirms that collagenolytic activity is inversely correlated with the hemoglobin content.