Dose-Response of Lymphocytes to Purified,Protein-Free Phytohemagglutinin: Lack of Metabolic Inhibition with Increasing Concentrations 1

Abstract

Summary

An essentially protein-free preparation of PHA prepared by the method of Goldberg et al. from Phaseolus vulgaris was tested for its ability to stimulate RNA-and DNA-synthesis in lymphocytes. It was noted that there is an increase in RNA- and DNA-synthesis with an increase of the dose of PHA until a plateau is reached. Even increasing the amount of PHA by many-fold does not lead to a decrease in RNA- and DNA-synthesis, which is in contrast to the properties of previously described protein-containing preparations of PHA. It is concluded that the depression of metabolic activity by more than optimal doses of protein-containing PHA preparations is due to toxic contaminants and not due to the RNA- and DNA-synthesis-stimulating principles themselves.