The Long Evans Cinnamon (LEC) rat develops hepatocellular damage in the absence of antimicrosomal antibodies

Long Evans Cinnamon (LEC) rats are an inbred strain with a mutation affecti ng a copper transporter. As a result, hepatic copper levels rise and the ra ts spontaneously develop hepatitis that is fatal in about 40% of the rats. The rats that die have been reported to develop anti-microsomal antibodies, most frequently against protein disulfide isomerase (PDI), prior to the on set of liver damage. The association between the presence of antibodies and death of the LEC rats, along with the detection of antibodies prior to the detection of liver damage suggested that the antibodies may have a role in the pathogenesis of liver damage. The objective of this study was to more clearly delineate the temporal relationship between antibody production and the onset of liver damage and copper accumulation. Serum was screened for the presence of anti-microsomal antibodies by immunoblotting. Liver damage was assessed by serum biochemistry and histological examination on rats bet ween 6 and 12 weeks of age (four per group). Copper accumulation in the liv er was determined by biochemistry and histological examination. Evidence of liver damage was detectable by serum biochemistry and histopathology by 11 .5 weeks. Copper was rarely detected in hepatocytes, although it was detect ed in macrophages. Sera from only one of seven rats with evidence of liver damage had detectable anti-microsomal protein antibodies. The protein recog nized was not PDI. The development of anti-microsomal autoantibodies did no t precede the development of significant liver damage, suggesting that they play only a secondary role, if any, in the pathogenesis of hepatitis in th is rat strain. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.