DETECTION OF ANTIBODIES AGAINST PROTEINS MODIFIED BY HYDROXYETHYL FREE-RADICALS IN PATIENTS WITH ALCOHOLIC CIRRHOSIS

Background/Aims: We have previously shown that hydroxyethyl free radic als produced during cytochrome P4502E1-mediated oxidation of ethanol c ovalently bind to microsomal proteins, The present study examined whet her alkylation of proteins by hydroxyethyl radicals induces an immunol ogic response in alcoholic patients, Methods: A microplate enzyme-link ed immunosorbent assay was developed using as antigen human serum albu min or bovine fibrinogen reacted with chemically produced hydroxyethyl radicals, Results: This assay showed that the sera of alcoholic cirrh otics contained both immunoglobulin (Ig) Gs and IgAs that recognized p roteins modified by hydroxyethyl radicals, whereas practically no reac tion was observed in the sera of healthy controls or cirrhotics withou t evidence of alcohol abuse, The reactivity of the sera from alcoholic patients was not influenced by the protein to which hydroxyethyl radi cals were bound, The sera of alcoholic cirrhotics also contained antib odies directed against acetaldehyde-modified albumin. However, the rea ction of alcoholic sera with hydroxyethyl radical epitopes was not inh ibited by increasing concentrations of acetaldehyde-modified albumin p roduced under either reducing or nonreducing conditions, Conclusions: The results indicate that a new group of antigens that do not cross-re act with antibodies against acetaldehyde-derived epitopes is formed by the alkylation of protein by hydroxyethyl radicals and is involved in the develop ment of immunologic reactions in alcoholic patients.