Hormonally Active Agents in the Environment (1999) / Chapter Skim
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7 Immunologic Effects
7 Immunologic Effects
Pages 186-209
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From page 186... ...
could mediate nonspecific, stress like effects. In the case of steroid hormones, it is clear that the actions of estrogens and androgens are important in the reported differences in immune response between male and female laboratory animals (Batchelor and Chapman 1965; Terres et al.
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From page 187... ...
Immunologic differences are also observed between pregnant and nonpregnant females. Immune responses in pregnant women are depressed compared with nonpregnant women.
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From page 188... ...
Laboratory Studies Specific examples of the immunologic effects of PCBs and TCDD on laboratory animals are detailed in Table 7-2. These HAHs cause atrophy of the thymus, the primary lymphoid organ in which stem cells are selected and differentiated into T-cells.
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From page 189... ...
Field Studies An observational study was conducted between 1992 and 1994 to determine whether contaminant-associated immunosuppression occurs in prefledgling Caspian terns and herring gulls of the Great Lakes (Grasman et al.1996~. The phytohemagglutinin skin test for T-cell mediated immunity was conducted on 3-wk-old chicks at colonies distributed across a broad gradient of organochlorine contamination (primarily PCBs)
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From page 194... ...
(1994,1996) reported that innate and acquired immune responses were functionally impaired in harbor seals fed herring from PCB-contaminated waters (Baltic Sea)
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From page 195... ...
The resulting effects were related primarily to increased respiratory infection; decreased serum concentrations of IgA and IgM; decreased CD4+ T-cells and increased CD8+ Tcells; suppressed dermal delayed hypersensitivity responses to a combination of streptokinase and streptodormase and to tuberculosis antigens; and augmentation of the in vitro lymphocyte mitogen stimulation to phytohemagglutinin (PHA) and pokeweed mitogen (PWM)
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From page 196... ...
DDT has been demonstrated to trigger some immunologic effector mechanisms in animal and bird models (Barrett and Rodgers 1994~. In studies of harbor seals, a diet of DDT-contaminated fish from the Baltic Sea was shown to impair immune response, as measured by delayed hypersensitivity in the skin to ovalbumin and in vitro lymphocyte assays (de Swart et al.
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From page 198... ...
(1993) reported that 95-100% of malnourished rats fed 5 mg/kg/d died; that 0.5 mg/kg/d decreased body weight and increased spleen weight; that both malnutrition and chlordecone increased PFC; and that 0.5 and 5 mg/kg/d plus a calcium diet increased PFC response, but that 5 mg/kg/d plus a protein diet decreased PFC response.
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From page 202... ...
In inhalation studies, chlordane administered at 1 or 10 mg/m3 for 90 d increased lymphocyte numbers in female rats; in vitro tests that used 10 M chlordane showed mitogenic activity. In addition, prenatal exposure to chlordane was reported to alter immune responses such as delayed hypersensitivity, macrophage activation, and colony-forming unit activity in offspring of exposed rats.
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From page 203... ...
HEXACHLOROBENZENE Exposure to hexachlorobenzene has been reported to produce histologic changes in lymphoid tissue architecture in laboratory animals.
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From page 207... ...
Reported effects from lindane encompass both the specific and the nonspecific arms of the immune system, and in laboratory animals such responses have included effects on humoral and cell-mediated immunity. Exposure to endosulfan in laboratory studies also has produced immunotoxic effects on nonspecific immunity and altered humoral and cell-mediated responses.
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From page 208... ...
RECOMMENDATIONS Based on the committee's review of the extensive laboratory animal data on immunologic effects of HAAs, as well as the limited information from wildlife and human studies, the following are recommended: Comprehensive epidemiologic studies that evaluate a variety of health effects, including immunologic effects, of human populations suspected of being affected by HAAs should be initiated. Especially needed are studies of cohorts established either through registries or directed effort to assess the prevalence of autoimmune problems in offspring whose mothers were exposed during pregnancy.
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From page 209... ...
IMMUNOLOGIC EFFECTS 209 of lymphocyte cytokine production and possibly mitogenic responsiveness; and the lytic action attributed to cytotoxic lymphocytes and natural killer cells in exposed populations to clarify the relationship between HAA exposure and human health. Because much of the available immunologic laboratory data on HAAs is on chemicals that have been regulated and, in most cases, are no longer used in the United States, future studies should focus on chemicals that are being used, such as endosulfan and lindane.
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