Erythrocyte and plasma protein modification in alcoholism: A possible role of acetaldehyde

Analysis of the oxidative modification of plasma and erythrocyte ghost proteins of chronic alcoholic subjects and healthy non-alcoholics has been performed. It was found that increased levels of protein carbonyls in both plasma and erythrocyte ghosts from alcoholic subjects occurred in comparison to the levels found in preparations from non-alcoholics. Plasma proteins from alcoholic subjects did not show evidence of cross-linking, although plasma protein concentration and composition were changed. In alcoholic subjects who displayed no evidence of abnormal erythrocyte morphology no cross-linking of erythrocyte ghost proteins was detectable, whereas the ghosts obtained from alcoholic subjects who displayed morphologically abnormal erythrocytes contained cross-linked proteins. The in vitro treatment with acetaldehyde of erythrocytes from non-alcoholics caused increased levels of protein carbonyls and cross-linking products in erythrocyte ghost preparations which were similar to those found in severe alcoholics. It is concluded that chronic alcohol consumption can cause abnormal erythrocyte morphology and increased erythrocyte fragility as a result of oxidation and cross-linking of erythrocyte ghost proteins. These effects can be ascribed, in part, to exposure of erythrocytes to circulatory acetaldehyde which is a product of ethanol metabolism.