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Conversion of Acetaldehyde‐Protein Adduct Epitopes From a Nonreduced to a Reduced Phenotype by Antigen Processing Cells
Author(s) -
Klassen Lynell W.,
Jones Bonnie L,
Sorrell Michael F.,
Tuma Dean J.,
Thiele Geoffrey M.
Publication year - 1999
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1111/j.1530-0277.1999.tb04167.x
Subject(s) - epitope , adduct , keyhole limpet hemocyanin , antigen , chemistry , monoclonal antibody , antibody , biochemistry , acetaldehyde , microbiology and biotechnology , in vitro , biology , immunology , ethanol , organic chemistry
Many investigators have suggested that an immune reaction to acctaldchydc‐protein adducts may be involved in the development and/or progression of alcohol liver disease. The most often reported acetaldehyde adduct is the reduced adduct prepared in vitro in the presence of strong reducing agents. However, the production of this adduct in vivo has been difficult to prove. Nevertheless, the detection of scrum antibodies to this reduced adduct following alcohol exposure in animals and humans has been used to support the formation of this adduct in vivo. We have recently observed that when acetaldehyde‐protein adducts prepared under nonrcducing conditions are used to immunize animals, antibody to the reduced protein adduct is detected. Therefore, it was the purpose of this study to demonstrate that nonreduced (NR) adduct epitopes can be modified by intact cells to express reduced (R) adduct epitopes. This was accomplished using the monoclonal antibody RT1.1 that has been previously characterized by this laboratory and has been shown to recognize only R and not NR acetaldchyde adducts. In these studies, Balb/c mice were injected intraperitoneally (500 μg/animal) with either keyhole limpet hemocyanin (KLH)‐NR or KLH‐R adductcd proteins. Immunization with KLH‐NR produced significant amounts of antibodies that recognized both NR and R epitopes. In contrast, immunization with KLH‐R produced antibodies to only R and not NR epitopes. Isolated peritoneal macrophages from nonimmunized mice were incubated in vitro with either KLH‐NR, KLH‐R, or unmodified KLH proteins, and the cell surface expression of the reduced epitope (RT1.1) and the activated macrophage marker (MAC‐3) determined by double immunofluores‐cent staining. Activated macrophages incubated with KLH‐NR expressed the R adduct on 11.5% of the cells, compared with 3.8% following incubation with unmodified KLH, and 19.4% following incubation with KLH‐R. These data suggest that the NR adduct and/or the carrier protein are modified by peritoneal macrophages in vivo and present an epitope that is detected as a reduced adduct (RT1.1 positive). These observations may explain the presence of circulating antibodies to the reduced adduct that has been reported in human and animal studies.