EFFECTS OF ETHANOL ON HUMAN NATURAL-KILLER-CELL ACTIVITY - IN-VITRO AND ACUTE, LOW-DOSE IN-VIVO STUDIES

Chronic use of ethanol may cause a variety of immunological abnormalit ies in humans. In this study, we have determined the effects of an acu te, low dose of ethanol (0.5 g/kg), administered either intravenously or orally, to normal, nonalcoholic male volunteers, on natural killer cell (NK) activity. We have also examined the effects of a 4-hr incuba tion with ethanol, in concentrations ranging from 0 to 320 mg/dl, on h uman NK activity in vitro. NK activity was measured by the Cr-51 relea se assay technique in all of these studies, using peripheral blood mon onuclear cells prepared from brood obtained from healthy, nonalcoholic volunteers. Eight subjects received ethanol in vivo; cells from nine subjects were used for the in vitro studies. Blood ethanol concentrati ons were determined at multiple time points before and after ethanol a dministration for the in vivo studies; for the in vitro studies, ethan ol concentrations were measured from each assay sample both before and after the incubation period. Gas chromatography was used for determin ations of both blood alcohol and medium ethanol concentrations. Result s of the in vivo studies showed that a single dose of ethanol (0.5 g/k g), administered either intravenously (with resultant peak blood level s transiently up to 89 mg/dl) or orally (with resultant peak blood lev els transiently up to 40 mg/dl at the time of the NK assay), did not a lter NK activity. However, results of the in vitro studies showed a si gnificant dose-dependent decrease (p < 0.001) in NK activity when etha nol exposure was sustained for 4 hr at concentrations of 80 mg/dl and above. We conclude that one of the possible causes for a higher incide nce of certain viral infections and malignant tumors among chronic alc oholics may be due, in part, to this observed direct effect of ethanol on NK cytotoxicity.