Incubation of peripheral blood or isolated lymphocytes of C57L/J mice with phytohemagglutinin stimulated the incorporation of thymidine into DNA of lymphocytes as they transformed into large lymphoblasts. DNA synthesis began after about 24 hr of incubation and reached a peak at 48 hours. The de-novo synthesis of sterols from acetate was stimulated much earlier, at 4 hr of incubation, and the ra...

The binding of phytohemagglutinins from Phaseolus vulgaris (erythroagglutinating phytohemagglutinin (E-PHA) and leukoagglutinating phytohemagglutinin (L-PHA)) and from Lens culinaris (lentil-PHA) to human platelet cell surfaces has been demonstrated. Each platelet binds on an average 500,000 to 600,000 molecules of E-PHA with an apparent dissociation constant of 0.5 X 10m7 M. These values were ...

The association of a human genetic deficiency of adenosine deaminase activity with combined immunodeficiency prompted a study of the effects of adenosine and of inhibition of adenosine deaminase activity on human lymphocyte transformation and a detailed study of adenosine metabolism throughout phytohemagglutinin-induced blastogenesis. The adenosine deaminase inhibitor, coformycin, at a concentr...

The need for agents designed to modify immune response in the treatment of patients with viral infection, immunodeficiency, or cancer prompted the present study on the mechanisms of action of isoprinosine, a compound developed for antiviral use and whose therapeutic activity may involve the immune system. The effect of isoprinosine on in vitro proliferation of human peripheral blood lymphocytes...

The RNA synthesis of human leukemic leukocytes and phytohemagglutinin-stimulated lymphocytes is markedly reduced by administration of a low-molecular-weight nonhistone peptide factor from calf thymus. Treatment with the factor strongly inhibits hemoglobin production and globin mRNA transcription in dimethyl sulfoxide-stimulated Friend cells without appreciably modifying the rate of cell growth....

Phytohemagglutinin, the lectin of the common bean Phaseolus vulgaris, has a high mannose and a modified (fucosylated) oligosaccharide on each polypeptide. Fractionation by high performance liquid chromatography of tryptic digests of [(3)H]fucose or [(3)H]glucosamine labeled phytohemagglutinin, followed by amino acid sequencing of the isolated glycopeptides, shows that the high mannose oligosacc...

Valinomycin is a depsipeptide antibiotic which selectively translocates potassium across biologic membranes. This potassium ionophore was observed to inhibit phytohemagglutinin-stimulated blastogenesis and proliferation in human lymphocytes. The effect was not due to toxicity to the cells, nor appeared to be due to the effects of valinomycin as an uncoupler of oxidative phosphorylation. Further...

Suspensions of cells from Hodgkin disease which formed nonimmune E rosettes with tumors were separated by velocity sedisheep red blood cells, they showed a lack mentation in an isokinetic Ficoll gradient. of responsiveness to phytohemagglutinin The separated cells were cultured with which was almost complete in all but one mitogens. The modal population of lympatient. Lymphocytes which had been...