Abstract
A gene encoding the variable regions of the heavy and light chains of a mouse monoclonal antibody H2, which specifically reacts with human liver cells, was cloned in a phagemid vector. Anti-idiotypic antibody was produced by immunizing the original mouse antibody with various absorptions. The cloned phage specifically reacted with this anti-idiotypic antibody, and the reaction between the cloned phage and anti-idiotypic antibody was specifically blocked by the original antibody. The soluble protein, expressed as a fusion protein, was detected as a 30 kDa single band on sodium dodecyl sulfate polyacrylamide gel electrophoresis. This protein was demonstrated to bind specifically to an anti H2 idiotypic antibody by Western blot analysis.
The sera of patients with various diseases were assayed using this anti-idiotypic antibody and sandwich enzyme-linked immunosorbent assay. Only the sera of patients with chronic liver diseases highly reacted and this binding was specifically attenuated by the cloned soluble protein. This liverspecific idiotype-bearing antibody detected in the serum of a patient with chronic hepatitis C could be purified and this antibody mediated antibody-dependent cytotoxicity against a hepatocyte derived cell line Chang in vitro.
These findings suggest that a human antibody that reacts with human liver cells, can be detected in patients with chronic liver diseases and can contribute to the liver cell damage.
