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 killer (NK) cells have not previously been examined in mice or humans. In the present study, a single dose of EtOH (5.0-7.0 g/kg) was administered 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 longer 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 suppression 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 decrease in the total number of splenocytes. However, the decrease in the percentage of NK cells was significantly less than the decrease in NK cell activity, suggesting an effect on NK cell activity as well as NK cell number. Splenic T cells were not depleted, but B cells were significantly decreased at the highest EtOH dose. Enhancement of NK activity after in vivo administration of polyinosinic-polycytidilic acid was blocked by EtOH (6.0 g/kg). These results indicate acute exposure to EtOH decreases basal and induced splenic NK cell activity in mice and that loss of NK cells at least partially explains the decrease in basal NK cell activity.