The HL-60 (Human promyelocytic leukemia cells) cell line is a leukemic cell line that has been used for laboratory research on how certain kinds of blood cells are formed. HL-60 proliferates continuously in suspension culture in nutrient medium supplemented with fetal bovine serum, L-glutamine, HEPES and antibiotic chemicals. The doubling time is about 36–48 hours. The cell line was derived from a 36-year-old woman with acute promyelocytic leukemia at the National Cancer Institute.[1] HL-60 cells are predominantly a neutrophilic promyelocyte (precursor).[1]
Proliferation of HL-60 cells occurs through the transferrin and insulin receptors, which are expressed on cell surface. The requirement for insulin and transferrin is absolute, as HL-60 proliferation immediately ceases if either of these compounds is removed from the serum-free culture media.[2] With this line, spontaneous differentiation to mature granulocytes can be induced by compounds such as dimethyl sulfoxide (DMSO), or retinoic acid. Other compounds like 1,25-dihydroxyvitamin D3, 12-O-tetradecanoylphorbol-13-acetate (TPA) and GM-CSF can induce HL-60 to differentiate to monocytic, macrophage-like and eosinophil phenotypes, respectively.
The HL-60 cultured cell line provides a continuous source of human cells for studying the molecular events of myeloid differentiation and the effects of physiologic, pharmacologic, and virologic elements on this process. HL-60 cell model was used to study the effect of DNA topoisomerase (topo) IIα and IIβ on differentiation and apoptosis of cells[3] and is especially useful in dielectrophoresis studies,[4] which require an aqueous environment with suspended and round cells.