Abstract |
The authors previously demonstrated that the glycol ether 2-methoxyethanol (ME) is immunotoxic in the rat. In the study, the immunotoxicity of 2-methoxyacetic acid (MAA), the principal metabolite of ME, was evaluated in adult male Fischer 344 rats. Rats were dosed by gavage with MAA on 10 consecutive days at dosages ranging from 50 to 200 mg/kg/day. Thymic involution, in the absence of body weight loss, was observed at 100 and 200 mg/kg/day MAA. Lymphoproliferative responses to the mitogens concanavalin A. phytohemagglutinin, and pokeweed mitogen were also reduced at these dosages. The in vitro generated cytotoxic T lymphocyte response was reduced at 200 mg/kg/day MAA. The mixed lymphocyte reaction and natural killer cell activity were unaffected by exposure to MAA. Enumeration of splenic lymphocyte populations revealed a reduction in the percentage of W3/25-positive cells at 100 and 150 mg/kg/day and an increase in the percentage of OX39-positive cells at 200 mg/kg/day; however, no changes in the absolute number of either of these subsets were observed. The plaque forming cell (PFC) response to trinitrophenyl-lipopolysaccharide (TNP-LPS) was suppressed at 50-200 mg/kg/day MAA, while the PFC response to sheep red blood cells (SRBC) was elevated at 50 mg/kg/day. (Copyright (c) 1991 Society of Toxicology.) |