INTERPHASE RIBOSOMAL-RNA CISTRON SILVER STAINING IN REFRACTORY ANEMIAS WITH AND WITHOUT EXCESS BLASTS

Aim-To evaluate the haemopoietic function of bone marrow blood forming cells in human myelodysplastic syndromes (MDS) by silver staining of nucleolar organiser regions (AgNORs). Methods-Nucleoli were investigat ed in bone marrow blast cells and in erythroid, granulocytic, and mega karyocytic cells from 12 haematologically healthy subjects, and from 2 6 patients with MDS, including 14 with refractory anaemia (RA), nine w ith RA with excess blasts (RAEB), and three with RAEB in transformatio n (RAEB-t). The investigation was performed before treatment using a o ne step silver staining method. In each case 50 to 100 blasts, promyel ocytes, myelocytes, immature (pronormoblastic and basophilic normoblas tic) and mature (polychromatic normoblastic) erythroid elements, and m egakaryocytes were evaluated for the mean numbers of nucleoli and AgNO Rs per nucleus. Student's t test was used to compare the patient and c ontrol groups. Other statistical analyses were carried out by the comp uter assisted ''HEMA'' system. Results-Compared with controls, the num ber of AgNORs in blasts, promyelocytes, immature erythroid elements, a nd megakaryocytes was decreased, whereas in myelocytes and polychromat ic normoblasts it was similar. There was also a difference in the AgNO R scores in blood forming cells from patients with RAEB/ RAEB-t v RA. Conclusions-The loss of AgNOR sites in cellular series in MDS may resu lt from the decrease of their proliferative potential with disease pro gression, intrinsic defects in maturation, and extensive apoptosis.