To the incidence of nucleoli in circulating myeloblasts of patients suffering from acute myeloblastic, promyelocytic and myelomonocytic leukemias

Nucleoli were studied in circulating myeloblasts of myeloblastic (FAB M1, M 2), promyelocytic FAB M3) and myelomonocytic (FAB M4) acute myeloid leukemi as (AMLs) using a cytochemical procedure for the demonstration of RNA. In p atients untreated with cytostatic chemotherapy, myeloblasts of myeloblastic acute leukemias possessed less frequently "active large" nucleoli and more frequently "inactive" micronucleoli in comparison with other investigated types of AMLs. When myeloblasts were classified according to the presence o f functionally dominant nucleoli, the higher percentage of "terminal" myelo blasts containing only micronucleoli in this type of AML was significantly reduced in patients treated with the cytostatic chemotherapy. In patients s uffering from promyelocytic leukemia treated with cytostatic chemotherapy, the decreased percentage of myeloblasts containing functionally dominant ac tive large nucleoli was accompanied by the increased incidence of myeloblas ts with functionally dominant "resting" ring shaped nucleoli. In myelomonoc ytic AML no significant differences were noted between patients untreated o r treated with the cytostatic chemotherapy in the incidence of main nucleol ar types in myeloblasts and myeloblasts classified according to the presenc e of functionally dominant nucleoli. Thus a further biological specificity might exist among leukemic blasts in various types of AMLs which should be considered for a rational approach to the therapy of these malignancies. In addition, the cytostatic chemotherapy did not influence incidence of the n ucleolar asynchrony in myeloblasts of all investigated types of AML.