IMMUNOCHEMICAL DETECTION OF PROTEIN ADDUCTS IN MICE TREATED WITH TRICHLOROETHYLENE

Trichloroethylene has been shown to produce tumors in rodents and is a suspect human carcinogen. In addition, a number of case reports raise the possibility that trichloroethylene can induce an autoimmune disor der known as systemic sclerosis. To investigate whether covalent bindi ng of reactive trichloroethylene metabolites may be involved in the me chanisms underlying these toxic responses, we have developed a polyclo nal antibody that can recognize trichloroethylene-protein adducts in t issues. The antibody was prepared by immunizing a rabbit with dichloro acetic anhydride-modified keyhole limpet hemocyanin. Enzyme-linked imm unosorbent assay data indicated that the serum antibody recognized dic hloroacetic anhydride-modified rabbit serum albumin, but not unmodifie d protein. In addition, N-epsilon-dichloroacetyl-L-lysine was the most potent inhibitor of antibody binding to dichloroacetic anhydride-modi fied rabbit serum albumin, indicating that the antibody recognizes pri marily dichloroacetylated lysine residues. Immunoblots revealed the pr esence of two major trichloroethylene adducts at 50 and 100 kDa in liv er microsomal fractions from male B6C3/F1 mice treated with trichloroe thylene. The formation of trichloroethylene adducts was both dose and time dependent. Furthermore, the 50-kDa adduct was found to comigrate on a polyacrylamide gel with cytochrome P450 2E1. These data show that reactive metabolites of trichloroethylene are formed in, vivo and bin d covalently to discrete proteins in mouse Liver. The data also sugges t that one of the protein targets is cytochrome P450 2E1. Further stud ies will be necessary to elucidate the relationship between covalent b inding of trichloroethylene and trichloroethylene toxicity.