Detection of circulating antibodies to malondialdehyde-acetaldehyde adducts in ethanol-fed rats.
OBJECTIVE
Malondialdehyde and acetaldehyde react together with proteins and form hybrid protein conjugates designated as MAA adducts, which have been detected in livers of ethanol-fed rats. The aim of this study was to examine the immune response to MAA adducts and other aldehyde adducts during long-term ethanol exposure.


METHODS
Rats were pair-fed for 7 months with a liquid diet containing either ethanol or isocaloric carbohydrate. Circulating antibody titers against MAA adducts and acetaldehyde adducts were measured and characterized in these animals.


RESULTS
A significant increase in antibody titers against MAA-adducted proteins was observed in the ethanol-fed animals. Competitive inhibitions of antibody binding indicated that the circulating antibodies against MAA-modified proteins in the ethanol-fed rats recognized mainly a specific, chemically defined MAA epitope. Antibody titers to reduced and nonreduced acetaldehyde adducts were very low, and no significant differences were observed between ethanol-fed and control animals. Significant plasma immunoreactivity to not only MAA-adducted but also unmodified rat liver proteins (cytosol, microsomes, and especially plasma membrane) were also observed in the ethanol-fed rats.


CONCLUSIONS
Long-term ethanol feeding generates circulating antibodies not only against MAA epitopes but possibly also against unmodified, native (self) protein epitopes, suggesting that MAA adducts could trigger harmful autoimmune responses.
Xu
D
D
Department of Veterans Affairs Alcohol Research Center and Departments of Internal Medicine and Biochemistry & Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, USA.
Thiele
G M
GM
Beckenhauer
J L
JL
Klassen
L W
LW
Sorrell
M F
MF
Tuma
D J
DJ
D000079:Acetaldehyde / Q000276:immunology*; D000437:Alcoholism / Q000097:blood / Q000276:immunology*; D000818:Animals; D000906:Antibodies / Q000097:blood*; D000917:Antibody Formation; D000918:Antibody Specificity; D004797:Enzyme-Linked Immunosorbent Assay; D008297:Male; D008315:Malondialdehyde / Q000276:immunology*; D011506:Proteins / Q000276:immunology*; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values
D000906:Antibodies; D011506:Proteins; D008315:Malondialdehyde; D000079:Acetaldehyde