Detection and further characterization of a newly described microsomal autoantibody associated with chronic delta...

Sera from 162 patients with acute or chronic hepatitis and from patients with autoimmune diseases have been investigated for autoantibodies by indirect immunofluorescence on human and animal tissues. A small proportion (14.2%) of young patients with chronic delta hepatitis has been found positive for cytoplasmic staining which was maximal in hepatocytes and renal proximal tubules. This autoantibody has been found to react with microsomal antigenic determinant different from the classic liver-kidney microsomal LKM antigen as demonstrated by fluorescence absorption experiments with purified subcellular organelles and by fluorescence-blocking tests. The microsomal autoantibody displayed also organ and species-specificity different from those shown by the LKM-positive sera. The positive patients showed persistence of the microsomal autoantibody during the follow-up without other serological markers of autoimmunity. There was no evidence of a particular course of chronic delta hepatitis in patients positive for the microsomal autoantibody.