LSA - A NEW LIVER-SPECIFIC ANTIGEN IN THE RAT .2. IMMUNOLOGICAL AND BIOLOGICAL PROPERTIES

The immunological and biological properties of a liver-specific antige n (LSA) from rat liver are described. LSA gave interspecies cross-reac tions with liver extracts from several mammalian species, but no react ion of complete identify was observed. Moreover, no cross-reaction was found with chicken or frog livers, thus indicating the rather late ap pearance of LSA in the process of evolution. Experiments with fetal an d neonatal liver extracts have indicated that LSA appears late in feta l development and is always present at birth. The biological propertie s of LSA were explored by several independent approaches. LSAg-Ab immu noprecipitates were stained positively with carbon naphthoxycholine io dide, an indirect evidence of choline esterase activity. LSA was also found to bind bile acids, thus suggesting organic anion properties. Fi nally, LSA was detected in the circulation of rats with acute carbon t etrachloride- and galactosamine-induced hepatocellular injury. This LS A is immunologically distinct from hepatitis B antigen, alpha-fetoprot ein, carcino-embryonic antigen and, from each of several serum and liv er proteins tested.