title: Retinoids inhibit the mitogenic activity of tumour-promoting phorbol esters on human lymphocytes.
abstract: The tumour-promoting agents 12-0-tetradecanoylphorbol-13-acetate (TPA) and phorbol-12, 13-dibutyrate (PDB) I are potent mitogens for human peripheral blood lymphocytes. In contrast, the non-cocarcinogenic substance phorbol lacks lymphocyte-activating properties. Non-toxic levels of retinoic acid (RA) or retinyl acetate (RAt) inhibit the phorbol-ester-stimulated lymphocyte blastogenesis required the near-concurrent addition of retinoids. Differences in the sensitivity of phorbol-ester-stimulated lymphocyte subpopulations to the antagonistic action of RA or RAt, respectively, suggest that the inhibitory effect of retinoids may not be due to a common mode of action. Lymphocyte cultures may provide a useful model system for studies of the mechanisms of action of both phorbol esters and retinoids.
mesh_terms: D002352:Carrier Proteins / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects*; D008214:Lymphocytes / Q000187:drug effects; D008934:Mitogens / Q000037:antagonists & inhibitors*; D009369:Neoplasms / Q000139:chemically induced / Q000188:drug therapy; D010703:Phorbol Esters / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D010704:Phorbols / Q000037:antagonists & inhibitors*; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D002352:Carrier Proteins; D008934:Mitogens; D010703:Phorbol Esters; D010704:Phorbols; D014212:Tretinoin