Occurrence and significance of antibody to liver-specific membrane lipoprotein by double-antibody immunoprecipitation method in sera of patients with acute and chronic liver diseases.

A double-antibody immunoprecipitation method was developed for detecting antibody to liver-specific membrane lipoprotein (anti-LSP) in sera of patients with various liver diseases and primary nonhepatic autoimmune diseases. Liver-specific membrane lipoprotein prepared from normal rat livers was labeled with 125I (chloramine-T) and monospecific antibody raised in rabbits. Cross-reactivity and absorption studies demonstrated that the assay used was highly specific. The frequency and titer of anti-LSP were similar for HBsAg-positive and -negative patients with both acute and chronic liver diseases. Patients with chronic active hepatitis had the highest frequenzy (25 of 44 cases, 57%) when compared with those with chronic persistent hepatitis (5 of 23 cases, 22%) and nonalcoholic cirrhosis (8 of 21 cases, 38%). Of the anti-LSP positive cases, the mean titer in patients with chronic active hepatitis tended to be the highest. In patients recovered from acute viral hepatitis, anti-LSP was transiently positive (7 of 20 cases, 35%) in the acute phase. In those who progressed to chronic hepatitis, a late rise as well as an early rise occurred in 6 of 10 patients before the diagnosis was made. Two of 6 patients with primary biliary cirrhosis had anti-LSP, but none of 41 patients with other nonviral liver diseases and none of 60 patients with primary nonhepatic autoimmune diseases. These data indicate that an autoimmune reaction directed against LSP can be initiated during the acute phase of viral hepatitis and it may persist in chronic hepatitis in both HBsAg-positive and -negative cases.