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 deoxyribonudeotide, total nucleotide, and protein con tent of single mononuclear cells derived directly from the peripheral blood buffy coats of patients with infectious mono nucleosis were determined cytochemically by means of ultra microspectrophotometry and ultramicrointerferometry. A small fraction of cells in the populations derived from each patient was found to be in the 5-or G-2-phase of DNA synthe sis. 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 mononudear cells in the peripheral blood of patients with infectious mononucleosis. The evidence suggests that there might be one nondividing, non-KNA, and nonprotein-accumulating cell population; one dividing, and one nondividing, but RNA-and protein-accumulating popula tion in each of the specimens so examined. The population characterized by large total nucleotide and mass values ap peared 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 de rived directly from the peripheral blood huffy coats of pa tients with infectious mononucleosis were dearly similar to ‘Thesestudies were supported in part by research grants from the those previously described in populations of leukemic blast cells similarly derived directly from patients with acute leu kemia. These cytochemical observations may well indicate similarities in the growth kinetics of mononuclear blood cell proliferation in infectious mononucleosis and acute leukemia.