title: The inhibition of initial steps of lymphocyte transformation by cytochalasin B1.
abstract: CB was shown to inhibit the PHA-induced activation of rabbit lymph node lymphocytes as assessed by the incorporation of 3H-uridine into RNA or 3H-thymidine into DNA. This suppression was dose dependent with an optimum of 10 mug CB/ml (20, 8 muM). Mitogen-activated lymphocytes escaped the inhibitory effect of the drug when CB was added later than 1 hr after the addition of PHA. CB also suppressed the activation of membrane phospholipid metabolism which occurs among the earliest detectable changes in activated lymphocytes. Thus the incorporation of 14C-choline, 14C-acetate, or 14C-oleate into lecithin in the presence of PHA and CB was the same as the level of their incorporation in unstimulated lymphocytes. The increased incorporation of 14C-oleate into lecithin of the plasma membrane of activated lymphocytes was similarly prevented in the presence of CB. In contrast, CB exhibited no or only a marginal effect on the phospholipid turnover of unstimulated lymphocytes. Our results point to plasma membrane phospholipid metabolism as the possible site of CB interference with the lymphocyte activation.
mesh_terms: D000818:Animals; D003571:Cytochalasin B / Q000494:pharmacology*; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D005260:Female; D008198:Lymph Nodes / Q000276:immunology; D008213:Lymphocyte Activation / Q000187:drug effects*; D008297:Male; D011817:Rabbits; D013997:Time Factors
chemical_list: D003571:Cytochalasin B