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EFFECTS OF 2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN (TCDD) ON HUMORAL IMMUNITY AND LYMPHOCYTE SUBPOPULATIONS: DIFFERENCES BETWEEN MICE AND RATS
Citation:
Smialowicz, R., M. Riddle, W. Williams, AND J. Diliberto. EFFECTS OF 2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN (TCDD) ON HUMORAL IMMUNITY AND LYMPHOCYTE SUBPOPULATIONS: DIFFERENCES BETWEEN MICE AND RATS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-94/320 (NTIS PB94197167).
Description:
While the effect that TCDD has on humoral immunity in the mouse has been well documented, it has not been for the rat. n this study, the effect that TCDD has on the antibody plaque-forming cell (PFC) response to sheep red blood cells (SRBC) in adult female B6C3F1 mice and F344 rats was compared. ice or rats were given a single intraperitoneal injection of TCDD at doses ranging from 0.1 to 30 ug/kg, 7 days prior to intravenous immunization with SRBC. our days later the PFC response to SRBC was determined. ice showed a dose related suppression of the PFC response, with an ED50 of 0.71 ug/kg TCDD. n contrast, TCDD failed to suppress and in fact enhanced the PFC response to SRBC in rats at doses as high as 30 ug/kg. he inability of TCDD to suppress the PFC response in rats was unrelated to hepatic CYP1A1 and CYP1A2 induction which was detectable at doses of 1 and 0.3 ug/kg TCDD, respectively. here was no shift in the time to peak PFC response in rats dosed with TCDD, nor was the failure of TCDD to suppress the PFC response in rats related to gender or strain. henotypic analysis of thymocytes and splenic lymphocytes from TCDD-dosed (i.e., 3, 10 or 30 ug/kg) and SREC-immunized mice and rats revealed that CD4-CD8+ splenocytes were reduced in a dose related manner in rats only and that this reduction in CD4-CD8+ was accompanied by a dose related increase in IgM+ splenocytes. hese results demonstrate species differences in the effect of TCDD on the PFC response to SRBC which were unrelated to hepatic CYP1A1 or CYP1A2 induction, time to peak response, gender and strain. he failure of TCDD to suppress and in fact to enhance the PFC response in rats appears to be related to alterations in splenic CD4-CD8+ suppressor cells.