To the Maximal Nuclear Diameter and Cell Cycle Phase of Lymphoblasts or Myeloblasts in Patients Suffering from Acute Lymphoblastic and Myeloblastic Leukaemia. A Simple Morphological and Technical Note

The present study was undertaken to provide complementary information on the cell cycle of leukaemic lymphoblasts and myeloblasts based on the computer-assisted maximal nuclear diameter measurements. The measurements were carried out in “one-size cell layer” loci of bone marrow smears of patients suffering from B-cell acute lymphoblastic leukaemia (B-ALL), acute myeloblastic leukaemia with minimal differentiation (M0 AML), acute myeloblastic leukaemia without maturation (M1 AML), acute myeloblastic leukaemia with maturation (M2 AML) and chronic myeloid leukaemia (CML). The maximal nuclear diameter was also measured in peripheral blood mature lymphocytes of B-cell chronic lymphocytic leukaemia (CLL), which are known to be in the G0/G1 phase of the cell cycle. In contrast, the maximal nuclear diameter in lymphoblasts of patients with B-ALL was larger and reflected the S and G2 cell cycle phase. The largest incidence of myeloblasts with the smallest maximal nuclear diameter was in M0 AML. The smaller incidence of such cells was also noted in patients with M1 AML. Myeloblasts with larger nuclear bodies were present in M2 AML and CML. Thus, post-mitotic myeloblasts in G0 and G1 phase were characteristic of M0 and to a smaller extent of M1 AML. Myeloblasts with larger maximal nuclear diameter reflecting the S and G2 phase were dominant in M2 AML and CML. In summary, the nuclear size heterogeneity of leukaemic lymphoblasts and myeloblasts in bone marrow smears depends on various phases of the cell cycle classified according to the maximal nuclear diameter.