Clinical diagnosis in patients with smooth muscle antibodies. A study of a one-year material.

Out of 17 109 sera tested for autoantibodies by indirect immunofluorescence, 236 contained smooth muscle antibodies (SMA) with a titre of greater than or equal to 1/25. The majority of these sera, from 190 patients, reacted both with smooth muscle and renal glomeruli and the specificity of these SMA is against actin. 91% of high-titred sera (greater than or equal to 1/100) with IgG antibodies giving this staining pattern were derived from patients with chronic inflammatory liver disease, mainly chronic active hepatitis. In the group with a titre of 1/25, non-liver diseases such as joint diseases were more common and liver conditions occurred only in 55%. Sera with SMA of IgM class weremostly derived from patients with acute viral hepatitis.