Interphase ribosomal RNA cistron silver staining in refractory anaemias 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 investigated in bone marrow blast cells and in erythroid, granulocytic, and megakaryocytic cells from 12 haematologically healthy subjects, and from 26 patients with MDS, including 14 with refractory anaemia (RA), nine with RA with excess blasts (RAEB), and three with RAEB in transformation (RAEB-t). The investigation was performed before treatment using a one step silver staining method. In each 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 AgNORs per nucleus. Student's t test was used to compare the patient and control groups. Other statistical analyses were carried out by the computer assisted "HEMA" system.

Results: Compared with controls, the number of AgNORs in blasts, promyelocytes, immature erythroid elements, and megakaryocytes was decreased, whereas in myelocytes and polychromatic normoblasts it was similar. There was also a difference in the AgNOR 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 result from the decrease of their proliferative potential with disease progression, intrinsic defects in maturation, and extensive apoptosis.