Circulating cytotoxic protein generated after ethanol consumption: identification and mechanism of reaction with cells.

Serum obtained from healthy volunteers 6-7 h after consumption of 60-95 g of ethanol contained cytotoxic activity against mouse A9 cells and all of six human cell lines tested. Affinity chromatography of such sera demonstrated that at least some of the cytotoxic molecules consisted of altered albumin. Complexes formed by the reaction of 14C-acetaldehyde with 125I-labelled human serum albumin in vitro were also cytotoxic. After treatment with a reducing agent, sodium borohydride, the cytotoxicity of both post-alcohol serum and the acetaldehyde-albumin complexes fell sharply, suggesting that the cytotoxic activity resided in the unstable Schiff bases formed during the first stage of reaction between the acetaldehyde and proteins. A detailed analysis of the reaction between the double-labelled acetaldehyde-albumin complexes and K562 cells revealed that the cytotoxic activity resulted from the release of acetaldehyde from such complexes and the preferential binding of the free acetaldehyde to the target cells.