Continuous culture of seven new cell lines (SK‐L1 to 7) from patients with acute leukemia

Continuous suspension cultures of seven lines of cells derived from the blood of seven patients with acute leukemia who had large numbers of circulating leukemic cells are described. Three cultures have been growing for more than 18 months and the other four for more than six months. Two of the cultures were obtained from children with lymphoblastic leukemia and five from patients with myeloblastic or myelomonocytic leukemia. In one of the myelomonocytic cultures, after several weeks in vitro, some of the blasts originally present underwent partial differentiation into pseudoeosinophils; these later died out, to be replaced by continuously‐growing blasts. In all of the established cultures, the cells resembled primitive blast forms morphologically, were highly motile, had diploid or near‐diploid modal numbers of chromosomes, and had doubling times of between 20 and 70 hours.