Changes in Phospholipid Metabolism Which Occur as a Consequence of Mitogenic Stimulation of Lymphocytes

Abstract Streptokinase-streptodornase (SKSD) was found to stimulate the turnover of phosphate in phosphatidyl inositol (PI). Stimulation of phosphate incorporation into PI by phytohemagglutinin (PHA) in lymphocytes obtained by fractionation on a gradient of BSA correlated with stimulation of DNA synthesis which occurred after 3 days of culture with PHA. The results obtained with lymphocytes separated on gradients of bovine serum albumin suggest the presence of two populations of lymphocytes responding to PHA. The experiments demonstrate that the PHA-induced turnover of phosphate in PI in lymphocytes is not the result of agglutination, but rather a consequence of mitogenic stimulation. In contrast to the stimulation induced by PHA and SKSD in PI, tetanus toxoid was found to stimulate the incorporation of phosphate into phosphatidyl choline and phosphatidyl ethanolamine. This difference argues further for the specificity of the response to mitogens observed in lymphocyte phospholipids.