The effect of Escherichia coli L-asparaginase on phytohemagglutinin (PHA)-induced transformation of human lymphocytes was studied. Transformation was remarkably suppressed by the enzyme when it was added to the cul ture not later than 24 hr after its initiation. The effective concentration was more than 0.2 i.u./tube. Guinea pig serum and L-0-aspartohydroxamic acid, an L-asparagine analog, have...

To examine anti-tumor immunity in uremic patients undergoing regular hemodialysis, we designed this study using in vitro mononuclear cell (MNC) cultures, with human leukemic U937 cells as the target. MNC were collected and cultured from uremic subjects and age- and gender-matched healthy controls. Conditioned media from the cultures (MNC-CM) were collected after stimulation with various concent...

The expression of phaseolin and phytohemagglutinin (PHA) in the developing cotyledons of a normal (Greensleeves) and a PHA-deficient (Pinto 111) cultivar of Phaseolus vulgaris was investigated. Phaseolin mRNA translational activity and abundance were present at similar levels in both cultivars. In contrast, PHA mRNA translational activity and abundance in Pinto 111 were less than 1% of the leve...

Assays were performed that measured both the rate and extent (or total capacity) of transfer RNA methylases in extracts of lymphocytes cultured in the presence and absence of phytohemagglutinin (PHA). The tRNA methylases of human peripheral blood lymphocytes undergoing blastogenesis in culture with PHA had a fiveto sixfold increase in rate and a threeto sevenfold increase in extent of methylati...

Lymphocyte phytohemagglutinin (PHA) responsiveness was found suppressed in both rubella sero-negative and sero-positive recipients of RA 27/3 strain of live attenuated rubella vaccine; the suppression was readily demonstrable only when a suboptimal dose of PHA was applied in the test. Lymphocytes from sero-negative vaccinees, which initially showed little or no in vitro response to concentrated...

T lymphocytes are unresponsive to T cell receptor (TCR) stimulation during culture in spaceflight or ground-based microgravity analogs such as the rotating-wall vessel (RWV) bioreactor. The TCR-induced activation of a subset of T cells can be rescued in the RWV by co-stimulation with sub-mitogenic doses of phorbol ester (PMA). We report that PMA co-stimulation of primary human T cells cultured ...

Assays were performed that measured both the rate and extent (or total capacity) of transfer RNA methylases in extracts of lymphocytes cultured in the presence and absence of phytohemagglutinin (PHA). The tRNA methylases of human peripheral blood lymphocytes undergoing blastogenesis in culture with PHA had a fiveto sixfold increase in rate and a threeto sevenfold increase in extent of methylati...

We have studied cyclic adenosine 3',5'-monophosphate (cyclic AMP) concentrations in human peripheral blood lymphocytes after stimulation with phytohemagglutinin (PHA), isoproterenol, prostaglandins, and aminophylline. Purified lymphocytes were obtained by nylon fiber chromatography, and low speed centrifugation to remove platelets. Cyclic AMP levels were determined by a highly sensitive radioim...

Phytohemagglutinin (PHA) stimulated the rate of DNA synthesis in rabbit spleen cell suspensions. Unlike antigens, previous immunization to PHA was not necessary and the specific response could not be transferred by macrophages, although lymphocytes primed by incubation in PHA were able to stimulate other spleen cells not directly exposed to PHA. When rabbits were stimulated by in vivo immunizat...

The DNA-dependent RNA polymerase activities of isolated nuclei from lymphocytes were examined after stimulation with phytohemagglutinin (PHA). The nuclear fraction was prepared with Mg(++) or Mn(++) to distinguish between polymerase I (nucleolar) and polymerase II (nucleoplasmic). Distinction between polymerases II and III was obtained by the addition of alpha-amanitin to the reaction mixture. ...