ETHANOL AND NATURAL-KILLER-CELLS .2. STIMULATION OF HUMAN NATURAL-KILLER ACTIVITY BY ETHANOL IN-VITRO

A single ethanol ingestion of 1 g/kg by healthy individuals under cont rolled conditions does not inhibit and may stimulate fresh natural kil ler (NK) activity measured 16 hr later. However, ethanol inhibits fres h human NK activity when added to the lytic assay medium, as reported previously by other investigators. In contrast, using the same target (K562 erythroleukemia cells), peripheral blood mononuclear cells cultu red 3 days with 50 units/ml of interleukin-2 are no longer inhibited s ignificantly by the same concentration of ethanol that inhibited the f resh cells by 80%. When freshly isolated peripheral blood mononuclear cells, monocyte-depleted lymphocytes, or partially purified NK cells a re pre-exposed to ethanol in vitro for 1 to 7 days, washed, and assaye d for lytic activity against K562, the lytic activity is increased com pared with nonethanol-exposed cells incubated concurrently. This incre ase is not dependent on accessory cells, added cytokines, or cell grow th, and seems to be an intrinsic response of the NK subset to ethanol exposure. The finding of NK stimulation by ethanol, considered togethe r with the observation of NK cell loss in some chronic alcoholics, sug gests that loss of NK activity in the chronic alcoholic may result fro m cell loss rather than direct ethanol inhibition of NK activity.