Enzyme changes and polyribosome profiles in phytohemagglutinin stimulated lymphocytes.

W HEN HUMAN LYMPHOCYTES are treated with phytohemagglutinin ( PHA ) , an extract of the kidney bean Phaseolus vulgaris, they undergo morphologic transformation followed by mitosis.13 Cooper and Rubin4 have demonstrated a decrease in the amount of total RNA witin 30 minutes after the exposure of lymphocytes to PHA. This is immediately followed by an exponential increase in the synthesis of RNA which continues for at least 24 hours.4-6 After approximately 36 hours, the lymphocytes begin to synthesize DNA7 and this is followed by a mitotic peak between 60-72 hours.3 8 Previous repOrts91’ have demonstrated increased amounts of ribosomes and endo plasmic reticulum in lymphocytes stimulated with PHA. In a series of studies, Hirschhorn et al.12’13 demonstrated the increase in total activity of three lysosomal enzymes, acid f3-glycerophosphatase, acid phenolphthalein phosphatase, and aryl sulfatase which were concentrated in the large granular fraction of their sucrose homogenates. In addition, they were able to postulate that these enzymes found in the granular fraction might be membrane-bounded On the basis of increased activity when treated with a membrane disruptive agent, lysolecithin. Cough and Elves14 have demonstrated an increase in glutamic dehydrogenase activity, while Bloom et al.’5 showed increase in the specific activity of lactate dehydrogenase in PHA treated lymphocytes. The purpose of this investigation was to study 1 ) the effect of PHA treatment of lymphocytes upon the distribution and amount of several intracellular enzymes, 2 ) to obtain polyribosome profiles, and 3 ) to utilize these polysomes for studies of in vitro protein synthesis.