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IMMUNE FUNCTION IN ADULT RATS EXPOSED TO DBT IN DRINKING WATER
Citation:
DEWITT, J., C. B. COPELAND, AND R. W. LUEBKE. IMMUNE FUNCTION IN ADULT RATS EXPOSED TO DBT IN DRINKING WATER. Presented at Society of Toxicology Annual Meeting, New Orleans, LA, March 06 - 10, 2005.
Description:
Organotins are used commercially as agricultural pesticides, antifouling agents and stabilizers for polyvinyl chloride (PVC) pipe. Mono- and di-substituted methyl and butyltins, used in PVC pipe production, are of concern to the USEPA as they leach from supply pipes into drinking water and have been reported to cause multisystem toxicity. As part of an ongoing study to evaluate immunotoxic effects of organotins, we assessed immune function after dibutyltin dichloride (DBT) exposure. Individually housed adult male and female Sprague Dawley rats were given drinking water containing 0, 10 or 25 mg/L of DBT (final concentration) in 0.5% Alkamuls for 28 days. Water bottles were changed and water consumption was monitored twice weekly. Body weights (BW) were recorded weekly. Delayed-type hypersensitivity (DTH), primary and secondary antibody responses to sheep red blood cells, and natural killer (NK) cell activity were evaluated in separate groups on day 29. DBT consumption had no significant effect on BW although water consumption was significantly decreased in both sexes at 25 mg DBT/L, especially during the first two weeks. DTH response and NK cell activity were similar across all groups regardless of dose. Although IgM responses were similar in all groups, IgG responses were significantly elevated in males consuming 25 mg DBT/L compared to controls. Organotins are immunotoxic in adult and pre-weanling rats and although these data did not suppress the adult immune responses we examined, the elevated IgG responses we observed were similar to an enhanced antibody response observed by Smialowicz, et al. (1989, 1990) in F344 rats exposed to tributyltin oxide. This enhancement is not consistent with other studies that have demonstrated suppressed or no changes in antibody responses. Therefore, this study illustrates that the immunotoxic effects of organotins may be related to the age of the animal, exposure duration, timing of immunization, rat strain, and/or individual organotins. This abstract does not reflect EPA policy and was supported by UNC/EPA Cooperative Training Agreement CT829472.