SummaryThe proliferative characteristics of human acute leukaemia cells are reported and the relationships between the proliferative alterations and differentiation defect of these cells discussed. The proliferative activity of acute leukaemia cells was also studied in relation to cytostatic treatment.Emphasis is laid on the fact that in all cases of acute leukaemia the characteristic blast cells of the disease do not constitute a homogenous cell population but can be divided into various

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... asses with different kinetic and proliferative characteristics. It is also pointed out that all cytostatic treatment acts on the most actively proliferating classes and only indirectly on the non-proliferating classes.Finally, the need for more detailed study of DNA synthesis at chromosome and sub-chromosome level for the purpose of more fully understanding the response of leukaemic cells to the various chemiotherapies is underlined.