The Effect of Phytohemagglutinin on Leukocyte Cultures as Measured by P³² Incorporation in the DNA, RNA, and Acid Soluble Fractions

PHA, when added to human leukocyte cultures, results in DNA synthesis and cell mitosis. The addition to these cultures of fetal calf serum, indole-acetic acid, kinetin, estrogens, or a small clot did not duplicate the effect of PHA. Concentrations of chloramphenicol 3.05 x 10^-3 M, diphenylhydantoin 5 x 10^-5 M, and 6-mercaptopurine 1.3 x 10^-3 M resulted in inhibition of growth. Possible mechanisms of action of PHA have been considered. In addition, the possible use of the method described as an in vitro means of evaluating drug sensitivity in leukemia has been suggested.