Karyotype Studies on Human Leukemic Lymphoblasts In Vitro and as Serial Transplants in Neonatal Syrian Hamsters

Human leukemic lymphoblasts (CCRF-CEM) have retained a near-diploid modal chromosome number and extra D-group marker chromosomes through more than 4½ years of growth in continuous suspension cultures. Tumors resulting from implantation of these cells from both frozen stock and continuous cell cultures into neonatal Syrian hamsters, and maintained therein by serial heterotransplantation, gradually evolved into cell populations with near-tetraploid modal chromosome numbers, most members having retained the extra D-group chromosome noticed earlier.