Interphase ribosomal RNA cistron staining in chronic myeloid leukaemia.

Aim-To evaluate the haemopoietic function of bone marrow blood forming cells in human chronic myeloid leukaemia (CML) by means of silver staining of nucleolar organiser region (AgNOR).Methods-Nucleoli were investigated in bone marrow blast cells and in erythroid, granulocytic, and megakaryocytic cells from 10 haematologically healthy subjects and from 26 patients with chronic myeloid leukemia (17 in benign phase, nine with blast crisis). The investigation was done before treatment, by means of a one step silver staining method. In every case 50 to 100 blasts, promyelocytes, myelocytes, immature (pronormoblastic and basophilic normoblastic) and mature (polychromatic normoblastic) erythroid elements, and megakaryocytes were evaluated for the mean numbers of nucleoli and for the average number of AgNORs per nucleus. Student's t test was used to compare the patient and control groups. Other statistical analyses were carried out by means of the computer assisted "HEMA" system.Results-Compared with controls, activation of NORs was noticed only in CML blasts, while there was a decrease in NORs in the erythroid elements, promyelocytes, and megakaryocytes. The AgNOR score of polychromatic normoblasts and megakaryocytes started to decrease in the benign stage of CML, whereas a similar decrease in pronormoblasts, basophilic normoblasts, and promyelocytes was detected only in patients with CML blast crisis.Conclusions-The loss of AgNOR sites in cell series in CML may be related to intrinsic defects in their proliferation.