title: Transient inhibition of mixed lymphocyte reactivity by dieldrin in mice.
abstract: Dieldrin, a non-aromatic organochlorinated pesticide, was shown to be a potent modulator of the immune system. We had earlier demonstrated that mice treated with a single sublethal dose of dieldrin showed an impaired antibody response and reduced viral restriction mediated by macrophages. These dieldrin-induced immunosuppressive effects were shown to be dose dependent, when administered by the oral or intraperitoneal (i.p.) route. This study was undertaken to investigate the effect of dieldrin on the T-cell immune response. Lymphoid cells from mice injected i.p. 7 days earlier with 36 mg/kg body weight (0.6 LD50) dieldrin were assessed for their ability to recognize a foreign antigen and to proliferate in a mixed lymphocyte reaction (MLR) at 4, 7, 14 and 24 days post-treatment. We have demonstrated a strong but transient inhibition of MLR at 7 days after pesticide exposure. This effect was reversible and could not be attributed to a direct cell cytotoxicity, nor to the modulation of the T-cell ratio in lymphoid organs. Since the mitogen response was not impaired at this time point, we suggest that T-cell ability to recognize a foreign antigen can be altered by dieldrin, but not the proliferative potential of the cells.
authors.affiliation: Institut Armand-Frappier, Laval-des-Rapides, Québec, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Hugo
authors.forename: J
authors.initials: J
authors.lastname: Bernier
authors.forename: K
authors.initials: K
authors.lastname: Krzystyniak
authors.forename: M
authors.initials: M
authors.lastname: Fournier
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D004026:Dieldrin / Q000633:toxicity*; D005260:Female; D007958:Leukocyte Count; D008213:Lymphocyte Activation / Q000187:drug effects; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008810:Mice, Inbred C57BL; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology
chemical_list: D004026:Dieldrin