Leukemia-like Pattern of the DNA, RNA, and Protein Content of Individual Mononuclear Cells in the Peripheral Blood of Patients with Infectious Mononucleosis

Summary The deoxyribonucleotide, total nucleotide, and protein content of single mononuclear cells derived directly from the peripheral blood buffy coats of patients with infectious mononucleosis were determined cytochemically by means of ultramicrospectrophotometry and ultramicrointerferometry. A small fraction of cells in the populations derived from each patient was found to be in the S- or G-2-phase of DNA synthesis. The intercellular variation in the total nucleotide and the protein content per cell in these cell populations was greater than that in comparable populations of normal lymphocytes. There were indications for the presence of more than one kind of population of mononuclear cells in the peripheral blood of patients with infectious mononucleosis. The evidence suggests that there might be one nondividing, non-RNA, and nonprotein-accumulating cell population; one dividing, and one nondividing, but RNA- and protein-accumulating population in each of the specimens so examined. The population characterized by large total nucleotide and mass values appeared to be identical with the population of so-called atypical mononuclear cells, and may well be genetically distinct from the other mononuclear cells in such populations. The cytochemical patterns observed in these populations derived directly from the peripheral blood buffy coats of patients with infectious mononucleosis were clearly similar to those previously described in populations of leukemic blast cells similarly directly from patients with acute leukemia. These cytochemical observations may well indicate similarities in the growth kinetics of mononuclear blood cell proliferation in infectious mononucleosis and acute leukemia.