title: Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on T cell-derived cytokine production in ovalbumin (OVA)-immunized C57Bl/6 mice.
abstract: 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is known to suppress both cellular and humoral immunity. Effector T cell-derived type-2 cytokines, including IL-4 and IL-5, play pivotal roles in humoral immunity. Herein, we studied whether TCDD affects type-2 cytokine productions during the immune response. C57Bl/6 mice were intraperitoneally immunized with ovalbumin (OVA) and orally administered 5 or 20 microg TCDD/kg on Day 0, and then challenged with OVA on Day 21. Seven days later (Day 28), antigen-specific antibodies in plasma, and T cell-derived cytokines produced by splenocytes and proliferation of splenocytes upon ex vivo re-stimulation with OVA were investigated. The quantities of IgM class and IgG1 class OVA-specific antibodies in plasma were reduced by 5 or 20 microg TCDD/kg and by 20 microg TCDD/kg, respectively. While thymus weight and cellularity were reduced by 20 microg TCDD/kg, spleen weight and cellularity were not changed by either 5 or 20 microg TCDD/kg. The proportions of B and T cells in the spleen were not affected by TCDD exposure. On the other hand, splenocytes from mice treated with 5 or 20 microg TCDD/kg were shown to produce less IL-4 or IL-5 upon ex vivo re-stimulation with OVA. Production of the T cell growth factor IL-2 was also decreased in splenocytes from TCDD-treated mice. In contrast, the type-1 cytokine IFN-gamma was increased by TCDD. Twenty micrograms of TCDD/kg suppressed OVA- or T cell mitogen (Con A)-stimulated proliferation of splenocytes, but did not affect B cell mitogen (LPS)-stimulated proliferation. These results suggested compromised T cell activation and suppressed type-2 cytokine production by T cells to be involved in the impaired humoral immunity associated with TCDD exposure.
authors.affiliation: Environmental Health Sciences Division, National Institute for Environmental Studies, Onogawa, Tsukuba, Ibaraki 305-8506, Japan. keikon@nies.go.jp
authors.forename: Keiko
authors.initials: K
authors.lastname: Nohara
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Fujimaki
authors.forename: Shin ichi
authors.initials: Si
authors.lastname: Tsukumo
authors.forename: Kaoru
authors.initials: K
authors.lastname: Inouye
authors.forename: Hideko
authors.initials: H
authors.lastname: Sone
authors.forename: Chiharu
authors.initials: C
authors.lastname: Tohyama
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D002454:Cell Differentiation / Q000187:drug effects; D016207:Cytokines / Q000096:biosynthesis*; D005434:Flow Cytometry; D008213:Lymphocyte Activation / Q000187:drug effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010047:Ovalbumin / Q000276:immunology*; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology*; D013154:Spleen / Q000166:cytology / Q000187:drug effects; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*
chemical_list: D016207:Cytokines; D000072317:Polychlorinated Dibenzodioxins; D010047:Ovalbumin