Different types of smooth muscle antibodies in chronic active hepatitis and primary biliary cirrhosis: their diagnostic and prognostic significance.

The diagnostic and prognostic significance of the different types of serum smooth muscle antibodies (SMA) were investigated in sera of 24 patients with chronic active hepatitis (CAH) and 15 patients with primary biliary cirrhosis (PBC). SMA of IgG class were found in 92% of sera from patients with CAH but in only 20% of sera from PBC patients, whereas the incidence of IgM-SMA was higher in PBC (67%) than in CAH (38%). All six patients with the atypical cholestatic form of CAH has SMA of IgM class, whereas other CAH patients had SMA of mainly IgG class. SMA reacting with rabbit liver (bile canaliculus antibodies, BCA) and with rat glomeruli (glomerulus antibodies) were of anti-actin specificity and were more common in CAH than in PBC. Organ specific BCA or glomerulus antibodies were not found. Anti-actin antibodies were detected in the majority of the investigated sera by an immunoenzymatic anti-actin assay. The results suggest that the determination of SMA titres with heavy chain specific antisera may help in the assessment of diagnosis and prognosis of chronic hepatitis.