INTERPHASE RIBOSOMAL-RNA CISTRON STAINING IN CHRONIC MYELOID-LEUKEMIA

Aim-To evaluate the haemopoietic function of bone marrow blood forming cells in human chronic myeloid leukaemia (CML) by means of silver sta ining of nucleolar organiser region (AgNOR). Methods-Nucleoli were inv estigated in bone marrow blast cells and in erythroid, granulocytic, a nd megakaryocytic cells from 10 haematologically healthy subjects and from 26 patients with chronic myeloid leukemia (17 in benign phase, ni ne with blast crisis). The investigation was done before treatment, by means of a one step silver staining method. In every case 50 to 100 b lasts, promyelocytes, myelocytes, immature (pronormoblastic and basoph ilic normoblastic) and mature (polychromatic normoblastic) erythroid e lements, and megakaryocytes were evaluated for the mean numbers of nuc leoli and for the average number of AgNORs per nucleus. Student's t te st was used to compare the patient and control groups. Other statistic al analyses were carried out by means of the computer assisted ''HEMA' ' system. Results-Compared with controls, activation of NORs was notic ed only in CML blasts, while there was a decrease in NORs in the eryth roid elements, promyelocytes, and megakaryocytes. The AgNOR score of p olychromatic normoblasts and megakaryocytes started to decrease in the benign stage of CML, whereas a similar decrease in pronormoblasts, ba sophilic normoblasts, and promyelocytes was detected only in patients with CML blast crisis. Conclusions-The loss of AgNOR sites in cell ser ies in CML may be related to intrinsic defects in their proliferation.