Response of baboon peripheral blood lymphocytes to phytohemagglutinin: Time course and dose response relationships

Optimal conditions for studying phytohemagglutinin (PHA)-induced transformation of baboon peripheral blood lymphocytes were determined. Maximal stimulation, as determined by uptake and incorporation of tritiated thymidine (total cell and trichloroacetic-acid-precipitable radioactivity), occurred at a PHA level of 12.5 μg in a culture volume of 0.25 ml containing 2 X 10⁵ lymphocytes. Optimal stimulation occurred after a total incubation of 114 h, the last 18 h of which was in the presence of 1 μCi of the labeled DNA precursor per culture. While there was considerable variation in the extent of responsiveness of lymphocytes from individual animals, the shape of the dose-response and time-course curves for most mitogen concentrations was generally similar.