SPECIES AND STRAIN COMPARISONS OF IMMUNOSUPPRESSION BY 2-METHOXYETHANOL AND 2-METHOXYACETIC ACID

2-Methoxyethanol (ME) and its principal metabolite 2-methoxyacetic aci d (MAA) have been shown in our laboratory to be immunosuppressive in m ale Fischer 344 rats. In this study several strains of 12-week-old fem ale rats and mice were used to compare the immunosuppressive activity of equimolar concentrations of ME and MAA on the trinitrophenyl-lipopo lysaccharide (TNP-LPS) antibody plaque-forming cell (PFC) response, wh ich we previously demonstrated to be a sensitive end point. Female inb red Lewis, Fischer 344 and Wistar/Furth, and outbred Sprague - Dawley rats were dosed by gavage with either ME or MAA at dosages of 0.33 to 2.64 mmol/kg/day for 10 consecutive days. Female inbred C3H and C57BL/ 6J, hybrid B6C3F(1), and outbred CD-1 mice were similarly dosed with e quimolar dosages of 0.66 to 5.28 mmol/kg/day ME or MAA. All animals we re immunized on day 9 of dosing and PFC responses evaluated 3 days lat er. Suppression of the PFC response was observed in all strains of rat s at 2.64 mmol/kg/day ME or MAA. Lewis and Wistar/Furth rats were foun d to be the most sensitive strains with suppression at levels as low a s 0.66 mmol/kg/day ME or MAA. While ME and MAA dosing resulted in supp ression of the TNP PFC response in all the rat strains tested, such tr eatment did not suppress this PFC response in any of the mouse strains examined. These results indicate that under the conditions of this st udy rats, but not mice, are immunosuppressed by ME and MAA exposure, a nd that the susceptibility to immunosuppression differs among rat stra ins.