Ethanol oxidation in Kupffer cells was investigated by measuring 14C-acetate formation from 14C-ethanol, and the role of aldehyde dehydrogenase 2 (ALDH2) in this process was also examined. Formation of 14C-acetate from 20 mM of 14C-ethanol was significantly increased in medium-containing Kupffer cells (9,003 +/- 2,066 cpm/5 x 10(6) cells), compared with medium containing no cells (1,826 +/- 46 cpm, p < 0.01), or containing acid-killed Kupffer cells (1,629 +/- 210 cpm, p < 0.01). Ethanol formation was significantly attenuated when 20 and 200 microM cyanamide or 2 microM disulfiram were given. Reverse transcriptase-polymerase chain reaction demonstrated that Kupffer cells carry mRNA for ALDH2. These findings indicate that Kupffer cells can oxidize ethanol to acetate. ALDH2 may participate in this process, especially in the conversion of acetaldehyde to acetate.