ETHANOL DECREASES THE NUMBER AND ACTIVITY OF SPLENIC NATURAL-KILLER-CELLS IN A MOUSE MODEL FOR BINGE DRINKING

The effects of acute administration of ethanol (EtOH) on natural kille r (NK) cells have not previously been examined in mice or humans. In t he present study, a single dose of EtOH (5.0-7.0 g/kg) was administere d by gavage to B6C3F1 mice. This produced maximum blood EtOH levels of approximately 0.25 to 0.50% (wt/vol). A single dose of EtOH decreased splenic NK cell activity (as measured by lysis of YAC-1 target cells in vitro). This decrease was maximal 12 hr after dosing and was no lon ger evident at 60 hr. Suppression of NK cell activity was consistently significant at EtOH doses of 6.0 or 6.5 g/kg, and significant suppres sion occurred in two of three experiments at doses of 5.0 or 5.5 g/kg. Flow cytometric analysis indicated a decrease in the percentage of NK cells in the spleen in EtOH-treated mice, and there was a small decre ase in the total number of splenocytes. However, the decrease in the p ercentage of NK cells was significantly less than the decrease in NK c ell activity, suggesting an effect on NK cell activity as well as NK c ell number. Splenic T cells were not depleted, but B cells were signif icantly decreased at the highest EtOH dose. Enhancement of NK activity after in vivo administration of polyinosinic-polycytidilic acid was b locked by EtOH (6.0 g/kg). These results indicate acute exposure to Et OH decreases basal and induced splenic NK cell activity in mice and th at loss of NK cells at least partially explains the decrease in basal NK cell activity.