Anti‐actin antibodies of IgM and IgG class in chronic liver diseases detected by fluorometric immunoassay*

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Abstract
ABSTRACT— Using a sensitive fluoroimmunoassay, anti‐actin antibodies (AA) of the IgM and IgG classes were measured in 240 patients with various chronic liver diseases and in 211 patients with non‐hepatic autoimmune muscle, heart, malignant and inflammatory bowel diseases. Thirty‐two out of 40 patients (80%) with autoimmune chronic active hepatitis (CAH) had AA only of the IgG class (geom. mean X = 1.78, SEM±0.07) and only three patients (8%) had both IgG and IgM AA, the latter in lower titres. In patients with primary biliary cirrhosis (PBC) and AMA‐positive cholestatic CAH, AA of both IgM and IgG classes were equally represented (60% IgG and 64% IgM AA in PBC, 73% IgG and 51% IgM AA in cholestatic CAH) but the titres were very low (geom. mean IgG AA in PBC 1.035, SEM±0.03, in cholestatic CAH 1.18, SEM±0.02). In contrast to autoimmune (lupoid) CAH, AA were rare in HBsAg positive CAH (9/43, 21%) and only present in low titres. However, in six out of 21 patients with anti‐HBs and anti‐HBc‐positive chronic active hepatitis, high AA of IgG class were found, suggesting the autoimmune type of liver disease. In NANB virus‐induced chronic liver disease after blood transfusion, AA were only occasionally found (IgG antibodies 1/19, IgM antibodies 3/19) and none were found in the eight patients with sporadic NANB hepatitis. They were also rare in 30 patients with alcoholic liver disease (3/30, 10%). Of 211 patients with non‐hepatic disorders, only 13 patients (6%) had AA (geom. mean of positive titres 0.076, SEM±0.01). We conclude therefore that high titre AA of the IgG class are reliable serological markers for the diagnosis of an autoimmune liver disease.