Contractile proteins as autoantigens.

Smooth muscle antoantibodies are found in high titre in some patients with chronic active hepatitis, and in lower titres in a number of other liver diseases and certain viral infections. They are directed at contractile proteins of the actomyosin group, and anti-actin activity appears to predominate. Whether occurring in disease affecting the liver or in other conditions, smooth muscle antibody production is thought to be stimulated when contractile proteins of non-muscle cells become immunogenic as a result of changes induced in the cells by viral infection or by other unknown causes of derangement of cytoskeletal structure.