ETHANOL-INDUCED OSMOLALITY CHANGES AND LYMPHOCYTE-PROLIFERATION

While there have been reports on the in vitro effects of ethanol ethan ol on mitogen-stimulated lymphocyte proliferation, little attention ha s been paid to whether these effects are mediated by the ethanol molec ule per se or the associated hyperosmolality. There is controversy whe ther ethanol at high concentrations inhibits or has no effect on mitog en-stimulated proliferation of T cells. In this study we sought to dis tinguish between effects due to ethanol and those related to increased osmolality. Rat splenocytes were cultured in vitro in hypertonic (gre ater than or equal to 320 mOsm) or isotonic (320 mOsm) ethanol solutio ns (tip to 400 mg/dL), or in corresponding hypertonic solutions withou t ethanol. Proliferative responses to the B cell mitogen lipopolysacch aride and the T cell mitogen concanavalin A were measured by mitochond rial dimethylthiazole diphenyl tetrazolium metabolism and [H-3]-thymid ine incorporation into DNA. B cell response was not significantly affe cted by ethanol under any conditions. By contrast, T cell proliferativ e responses were significantly inhibited by isotonic ethanol solutions or hypertonic solutions in the absence of ethanol, but nor by hyperto nic ethanol solutions. These results indicate that, while high osmolal ity is normally inhibitory to lymphocyte function, the increase in osm olality caused by ethanol is protective against the otherwise detrimen tal effects of ethanol.