Peripheral blood lymphocytes from normal donors and patients with chronic lymphocytic leukemia. B-cell type. were purified into T. helper T. and suppressor T lymphocytes by fluorescence-activated cell sorting using OKT3. 0KT4. and 0KT8 monoclonal antibodies. The maximum response of the purified subpopulations to stimulation by phytohemagglutinin (PHA) was determined by measuring the production ...

A Hodgkin cell-specific antigen detected by the monoclonal antibody Ki-1 was found on T helper lymphocytes after activation by autologous and allogeneic stimulator cells. About 50% of lymphoblasts generated by autoand alloactivation reacted with the antibody. In contrast. only less than 6% of lymphoblasts stimulated with Con-A. phytohemagglutinin (PHA). or protein A. and none of lymphoblasts

Human peripheral blood mononuclear cells (lymphocyte-monocyte) in culture release a solube factor which can stimulate, up to 200-fold, production of prostaglandin E2 by isolated, adherent, rheumatoid synovial cells. Production of the factor by the mononuclear cells is enhanced by phytohemagglutinin. This factor is similar in apparent mol vt (10,000-20,000) to that which also stimulates collagen...

L-Asparaginase is immunosuppressive, inhibiting both the cellular and humoral responses, as well as the concanavalin Aand/or phytohemagglutinin-induced blastogenesis of lymphocytes. However, its mechanism of action is presently unclear. This study dealt with the enzyme effects on the lymphocyte surface leading to interference with the binding of concanavalin A. The mitogen was labeled with ' 25...

The production of osteoclast-activating factor (OAF) by normal human peripheral blood leukocytes stimulated by phytohemagglutinin was inhibited by a series of structurally unrelated inhibitors of prostaglandin synthetase. Inhibition of OAF production by these agents was reversed by adding prostaglandins of the E series back to the leukocyte suspension. These results indicate that prostaglandin ...

Ribonuclease-sensitive DNA synthesis is demonstrated in a cytoplasmic particulate fraction of normal human blood lymphocytes stimulated with phytohemagglutinin, but not in unstimulated lymphocytes. DNA polymerase purified from this fraction does not transcribe the heteropolymeric regions of 70S RNA from RNA tumor viruses, thus distinguishing this enzyme from the RNA-directed DNA polymerase (rev...

Phytohemagglutinin stimulated human lymphocytes exhibit a 20 fold increase in DNA repair synthesis following ionizing radiation damage compared to the level of repair in unstimulated cells. The peak of repair synthesis coincides with that for DNA replication. Stimulated lymphocytes provide a relatively simple assay for ionizing radiation repair defects.

The influence of DDS on PHA-induced lymphocyte transformation was investigated in leukocyte cultures from two samples of healthy Caucasoid individuals. In one sample the sulfone-treated cultures differed from the controls in that they contained 0.4 mug/ml of other sample, the treated cultures contained DDS in concentrations of 4 mug/ml, 8 mug/ml and 16 mug/ml. The frequency of lymphocyte transf...

The DNA released into the culture medium after phytohemagglutinin (PHA) stimulation of human peripheral blood lymphocytes has been purified and characterized. It is double stranded, sediments at 7-8S in alkaline sucrose, and has a Tm determined optically and by thermal elution from hydroxyapatite that is substantially lower than that found for lymphocyte cell DNA. Media DNA contains a major com...