Human leukemic cells: Fractionation and characterization of ribonucleic acids

RNA extracted from log-phase human lymphocytic cells in large-scale cultures was purified and subjected to long (2.5 × 300 cm) exclusion chromatography (Sephadex G-100 columns) by a novel method which provided greater separation of the four main fractions, as well as separation of lower molecular weight species of RNA with a high degree of resolution. The molecular weights of each fraction were determined by polyacrylamide gel electrophoresis. Similar chromatographic patterns were obtained with RNA isolated from lymphocytic cells derived from patients with acute lymphocytic leukemia or infectious mononucleosis, and from normal healthy donors. Although these overall RNA patterns appeared to be similar, some quantitative differences in percentage distribution of individual RNA fractions were evident, in particular: the lower yield of higher molecular weight RNA (Peak I); and the higher yield of lower molecular weight species of RNA from human leukemic cells. In addition, nucleotide analyses revealed a higher ratio of A + U G + C in the 5.5S RNA Peak II fraction isolated from human leukemic (CCRF-CEM) cells as compared with that of lymphocytic cells derived from patients with infectious mononucleosis, or from normal donors. Despite these minor differences, the rather extensive homology between the same RNA species obtained from cells deriving from patients with acute lymphoblastic leukemia or infectious mononucleosis, and normal donors may be of biological significance. Nonetheless, more detailed studies should be undertaken to further characterize the RNA species characteristic of such human lymphocytic cells.