HL-60 is a promyelocytic cell line derived by S.J. Collins, et al. Peripheral blood leukocytes were obtained by leukopheresis from a 36-year-old Caucasian female with acute promyelocytic leukemia. The cells resemble promyelocytes. In vitro the cells can be induced to differentiate terminally into granulocyte-like cells or monocyte/macrophage-like cells, depending on the inducing agent. This cell line has been used as a model for human myeloid cell differentiation.