DISCRIMINATION OF HUMAN-LEUKEMIA SUBTYPES BY FLOW CYTOMETRIC ANALYSIS OF CELLULAR DNA AND RNA

Abstract

A newly developed flow cytometry technique for simultaneous measurements of 3 features of individual cells.sbd.DNA, RNA and nuclear diameter.sbd.using acridine orange as a fluorescent metachromatic dye, was applied to cell-cycle analysis, DNA stemline determination and to classification of 102 cases of human leukemias in adults. Acute lymphoblastic leukemia (L1-2) was characterized by moderately increased RNA of GO/1 cells as compared to normal lymphocytes; acute nonlymphoblastic leukemia (M 1-5) by very high RNA of G0/G1 cells. Both had diploid or aneuploid DNA stemlines. Chronic lymphocytic leukemia showed diploid DNA, very low proliferation and low RNA, similar to that typical for normal B [bone marrow-derived] cells. In chronic myelogenous leukemia 2 cell populations were distinguished, 1 with high RNA, the other with very low RNA and elongated nuclear diameter due to stripped, unfolded nuclei of polymorphonuclear leukocytes. The number of leukemic blast cells, identified by aneuploid DNA values, correlated well with conventional microscopy counts and could be followed during treatment. Acridine orange flow cytometry could be used to discriminate subtypes of human leukemias, to determine cell cycle stages and to detect and monitor aneuploid leukemia stemlines.