title: Suppressive effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the high-affinity antibody response in C57BL/6 mice.
abstract: In the humoral immune response to an invasion of foreign antigens, B cells differentiate into low-affinity antibody-forming cells (AFCs) that mainly secrete IgM or, through germinal center (GC) formation, into high-affinity AFCs that secrete IgG-class antibodies with a higher affinity for the antigen. Previous studies have established the suppressive effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on low-affinity antibody responses to antigens. However, whether and how TCDD affects the high-affinity antibody response to antigens has not yet been clarified. In this paper we investigate the effects of TCDD on GC formation, high-affinity AFC generation, and high-affinity antibody production in the primary humoral immune response. C57BL/6 mice were orally administered 0 or 20 microg/kg of TCDD and subsequently immunized with alum-precipitated ovalbumin (OVA) on day 0. Then the GC formation in the spleen and OVA-specific antibodies in the plasma, was evaluated until day 14 postimmunization. TCDD exposure reduced the production of OVA-specific IgG1 on days 10 and 14. GC formation in the spleen was also suppressed by TCDD exposure, and the suppression persisted from day 7 until day 14. In TCDD-administered mice, on day 7, cellular proliferation in the GCs was significantly suppressed, although apoptosis was not markedly affected. In order to measure high-affinity antibody and high-affinity AFCs, the mice were administered TCDD followed by immunization with alum-precipitated (4-hydroxy-3-nitrophenyl) acetyl linked to chicken gamma-globulin (NP-CG). The frequency of high-affinity NP-specific AFCs that bind to low-haptenated antigen was clearly shown to be reduced in the spleen on days 10 and 14. Furthermore, the high-affinity anti-NP IgG1 levels on days 10 and 14 postimmunization were significantly reduced by TCDD exposure. Taken together, the results of this paper demonstrate that TCDD exposure inhibits the generation of high-affinity AFCs and high-affinity antibody production during the primary humoral immune response and suggest that these alterations were caused by the suppression of antigen-responding B-cell proliferation induced by TCDD during GC formation.
authors.affiliation: Environmental Health Sciences Division, National Institute for Environmental Studies, Tsukuba 305-8506, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Inouye
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Ito
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Fujimaki
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Toshitada
authors.initials: T
authors.lastname: Takemori
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Pan
authors.forename: Chiharu
authors.initials: C
authors.lastname: Tohyama
authors.forename: Keiko
authors.initials: K
authors.lastname: Nohara
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000915:Antibody Affinity / Q000187:drug effects; D000917:Antibody Formation / Q000187:drug effects* / Q000276:immunology; D000921:Antibody-Producing Cells / Q000187:drug effects* / Q000276:immunology / Q000473:pathology; D004785:Environmental Pollutants / Q000008:administration & dosage / Q000633:toxicity*; D005260:Female; D005434:Flow Cytometry; D018858:Germinal Center / Q000187:drug effects / Q000473:pathology; D007074:Immunoglobulin G / Q000378:metabolism; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000633:toxicity*; D051379:Mice; D008810:Mice, Inbred C57BL; D010047:Ovalbumin / Q000276:immunology; D000072317:Polychlorinated Dibenzodioxins / Q000008:administration & dosage / Q000633:toxicity*; D013154:Spleen / Q000187:drug effects / Q000276:immunology / Q000473:pathology
chemical_list: D004785:Environmental Pollutants; D007074:Immunoglobulin G; D007166:Immunosuppressive Agents; D000072317:Polychlorinated Dibenzodioxins; D010047:Ovalbumin