title: Antagonistic regulation of cytotoxic T lymphocyte activation by prostaglandin E2 and L-ornithine.
abstract: Two macrophage-mediated immunoregulatory substances, prostaglandin E2 and L-ornithine, were found to mediate antagonistic effects. Both substances were previously shown to inhibit the activation of cytotoxic T lymphocytes under certain conditions. Our experiments now show that high doses of L-ornithine counteract the inhibitory effect of PGE2, and that PGE2 counteracts the inhibitory effect of high doses of L-ornithine; i.e. both substances can also augment cytotoxic responses in the presence of high concentrations of the other component. The direction of the immune regulatory effects of these substances is, therefore, expected to depend on the endogenous levels of PGE2 and L-ornithine in the individual animal at the site of immunization.
mesh_terms: D000818:Animals; D015232:Dinoprostone; D004336:Drug Antagonism; D007700:Kinetics; D008213:Lymphocyte Activation / Q000187:drug effects*; D051379:Mice; D009952:Ornithine / Q000494:pharmacology*; D011458:Prostaglandins E / Q000494:pharmacology*; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects / Q000276:immunology*
chemical_list: D011458:Prostaglandins E; D009952:Ornithine; D015232:Dinoprostone