The activity of nucleolar organizer regions of human bone marrow cells studied with silver staining. II. Acute leukemia.

The activity of nucleolar organizer regions (NOR) in chromosomes and interphase nuclei of bone marrow cells from 11 adult patients with acute lymphoblastic leukemia (ALL), 35 patients with acute nonlymphoblastic leukemia (ANLL), and eight healthy donors has been studied with silver nitrate staining. PHA-stimulated lymphocytes of the same individuals were used as standards of the maximum silver-staining patterns for each person. In 90% of patients with acute leukemia the average number of Ag+NOR in metaphases was lower when compared with that of PHA-stimulated lymphocytes. A variable expression of NOR was observed within the cell population and between individual patients. The populations tested showed high heterogeneity in relation to the content of Ag-negative mitoses. Ag+NOR per metaphase and the content of Ag-negative mitoses in bone marrow did not differ between patients with ALL and ANLL. Differences in the staining pattern in leukemic cells are discussed.