Activation of murine thymocytes in vivo. Part II: Study of blastogenesis, the synthesis of macromolecules and the cytotoxic response after stimulation with phytohemagglutinin.

To determine whether the polyclonal immunomodulator, Phytohemagglutinin (PHA), stimulates murine lymphocytes in vivo and causes cytotoxic differentiation, we studied blastogenesis and the concomitant synthesis of macromolecules (DNA, RNA and protein) by lymphocytes at different hours after injection of PHA in mice. 51Cr release assay was also performed by using allogeneic cells as target to determine whether lymphocytes after stimulation in vivo by this activator undergo cytotoxic differentiation. Out of the five doses of Phytohemagglutinin (2.5 micrograms, 5 micrograms, 10 micrograms, 20 micrograms and 50 micrograms per mouse) a marginally higher peak of blastogenesis was observed with 20 micrograms dose at 48 hr. No significant peak was observed in synthesis of macromolecules or with cytotoxicity.