Abstract
The human myeloblastic leukemia cell line, ML-1, can be induced differentiation to mature macrophage-like cells by dimethylsulfoxide and protein factors in human peripheral blood leukocyte conditioned medium (LCM) . We can identify the stage of differentiation by morphological characteristics and various markers which express cellular functional changes. In this presentation, after ML-1 cells have been preincubated with low concentration of Actinomycin D and other DNA synthesis inhibitors (Cylocide, Methotrexate, Adriacin), they are incubated with addition of 1% LCM for 3 days. ML-1 cells can be induced differentiation by LCM alone and express increasing NBT reducing activity. Preincubation with low dose of such compounds, ML-1 cells demonstrate extremely increasing NBT reducing activity and can be induced differentiation to mature macrophage-like cells. Such phenomenon also occurs when they have been radiated by ultraviolet rays for a few seconds, followed by incubation with 1% LCM. These results suggest that differentiation of ML-1 cells would consist of at least two processes. One process would inhibit DNA synthesis directly or indirectly, another process would influence on the cell membrane. Actinomycin D, other DNA synthesis inhibitors and UV radiation are the first process, concerned with DNA synthesis inhibition. Incubation with protein factors in LCM is the second process, concerned with the cell membrane. From clinical aspects, these findings will be considered important because such low dose of DNA synthesis inhibitors and protein inducers can reduce side effects in leukemic chemotherapy and leukemic cells can be induced differentiation more effectively.
