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THE ELISA: APPROACH TO ASSESS HUMORAL IMMUNITY FOR II~NJNOTOXICOLOGY

J e r r y H. Exon and Loren D. Koller Veterinary Medicine, University of Idaho, Moscow, Idaho 83843.

l-=,unotoxicology is becoming recognized and used by toxicologists involved in drug and chemical evaluations. The purpose of this study was to develop a highly sensitive, quantitative imunoassay that could assess the humoral iz~une response. The enzyme- linked immunosorbent assay (ELISA) proved to be not only highly sensitive and quantita- tive, simple t o perform, reliable economically feasible, required few test animals and automated. The antigens tested were bovine sera albumin and ovalbumin and the chemicals used to validate the system were lead, polychlorinated biphenyl, cyclophosphamide and dexamethasone, all of which were immunosuppresslve at the dosages tested.

FUNCTIONAL AND QUANTITATIVE EFFECTS OF 2,3,7,8-TETRACHLORODIBENZO-p-DIOXIN (TCDD) EXPOSURE ON THE CELL-MEDIATED I~(0NE SYSTEM IN MICE.

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J. D. Jackson and J. G. Sharp Dept. of Anatomy, Univ. of Nebr. Medical Center, ~2nd and Dewey, Omaha, ME 68105.

This study evaluates the effects of TCDD exposure on cell-mediated immune function and on T-cell subpopulations using indirect fluorescent staining with mono~lonal antibodies to specific T-cell surface-markers and flow cytometry. Female C57BI/6J mice were dosed weekly for 2 weeks by gastric intubation with 5 Mg/kg TCDD dissolved in 6 parts corn oil and 1 part acetone. Control animals were given the corn oil-acetone mixture only or were un- treated. One week following the last dose of TCDD, the mice were evaluated for ~une function utilizing mitngen, hemolytic plaque, and delayed type hypersensitivity (DTH) assays. The data indicate an overall decrease in spleen cell number and thymus weight in the TCDD-treated group with no apparent differences in the relative T-cell subpopulation frequencies in the spleen cell population. There also appears to be a decreased or sup- pression of spleen oell-medlated function as measured by mitngen, hemolytic plaque, and DTH assays. One may speculate that non-functional T-cell populations, not yet fully mature and in a regenerative phase are present in the spleen, or there is a specific suppressor cell population that has been generated during the treatment with TCDD. (Supported in part by UHMC Seed Grant f u n d s . )

~CESS DIETARY ZINC CAUSES RAIR LOSS AND SUPPRESSES THE IMMUNE RESPONSE IN SECOND GENERATION MICE. S.A. Mulhe rn , L .E. Magruder , S.T. J o n e s , and P . I . Rabbani Food and Drug Administration, Division of Nutrition, Washington, D.C. 20204

Second generation mice were exposed to normal levels of Zn (52.4 ppm, chow diet) or excess levels of Zn (2030 ppm, biotin-fortified egg white diet) in the maternal diet during gestation and lactation. The mice were weaned to their mother's diet and con- tinued on this diet until sacrifice at eight weeks of age. The levels of tibia Zn in the two groups reflected dietary intake. Plasma copper levels of the excess Zn group indi- cated copper deficiency. Both the excess Zn group and a third group exposed to excess Zn only from lactation developed a normal hair coat until approximately two weeks of age. Both of these groups then began to lose hair, but only on their back. Hair regrowth began at about six weeks of age and was lighter in color than that of age-matched contro)s. This suggests that dietary manipulation during gestation is not required to produce this phenomenon. Mice exposed to excess Zn throughout gestation and postnatal development did not have atrophied lymphoid organs. This group and the control group had similar Ig and Thy 1.2 profiles, demonstrating that splenic B and T cells are similar with respect to proportion and distribution of these markers. The excess Zn group did have reduced body weight and diminished plaque-forming cell response to sheep erythrocytes compared to the control group. The data suggests that excess Zn adversely affects hair growth and sup- presses The lu~nune response aurlng ontogeny.

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