title: Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on splenic lymphocyte transformation in mice after single and repeated exposures.
abstract: Male CD-1 mice were orally treated with 0.01, 0.1, 1 and 10 micrograms TCDD/kg body wt./week for up to 8 weeks. Randomly selected animals were sacrificed at 2, 4, and 8 weeks of exposure. An additional group was given orally 10 micrograms TCDD/kg and the animals similarly sacrificed. Splenic lymphocytes from these animals were cultured in vitro with or without the presence of phytomitogens, phytohemagglutinin, and pokeweed mitogen. The incorporation of 3H-thymidine was measured as an indication of relative blast formation. Exposure of animals to TCDD, even at the lowest level (0.01 microgram/kg/wk for 2 weeks) caused a marked increase in the thymidine uptake by cultured lymphocytes. The blastogenic response of mitogens was reduced at high levels of TCDD exposure, indicating an immunosuppressive effect. Following a single treatment with 10 micrograms TCDD/kg, the increase in the blast formation was noted at 2 weeks, the effect reduced at 4 weeks, and no difference noticed in treated vs. control cultures 8 weeks after the treatment. Small doses of TCDD stimulate the splenic lymphocyte transformation and this effect, although somewhat dose-related, can be reversed in a relatively short period of time.
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D004147:Dioxins / Q000494:pharmacology*; D007108:Immune Tolerance / Q000187:drug effects; D008099:Liver / Q000187:drug effects / Q000473:pathology; D008213:Lymphocyte Activation / Q000187:drug effects*; D008214:Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D008297:Male; D051379:Mice; D008934:Mitogens / Q000494:pharmacology; D009929:Organ Size / Q000187:drug effects; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology*; D013154:Spleen / Q000187:drug effects* / Q000473:pathology; D013950:Thymus Gland / Q000187:drug effects / Q000473:pathology
chemical_list: D004147:Dioxins; D008934:Mitogens; D000072317:Polychlorinated Dibenzodioxins; D004247:DNA