A sandwich enzyme immunoassay for liver-specific antigen and its forensic evaluation

We attempted to develop a method for the determination of liver injuries, using a liver-specific antigen as a marker. The liver-specific antigen (LSA) was purified from the human liver and the antibody to the human LSA only reacted with the liver extract using the immuno-dot-blotting technique. Depending on the immunohistochemical study, the LSA was found to be located within the cytoplasm of hepatocytes. A sensitive and specific sandwich enzyme immunoassay was then developed for the measurement of LSA. The detection limit of human LSA was 1 fmol/tube (52 pg/tube) and this assay was not affected by hemolysis. The LSA levels in serum and blood from healthy subjects were distributed within a range below the detection limit. The LSA levels in the blood from cadavers whose livers had been damaged, were markedly elevated in comparison with the normal levels found in other cadavers (10-140 fold). No cross-reaction was observed with the liver extracts from several species (mouse, rat, guinea pig and rabbit). These results suggest that the measurement of LSA levels in blood will become a useful marker for the detection of liver injury.