Smooth Muscle Antibodies and Anti-actin Autoantibody

Human smooth muscle antibodies (SMA) were first detected in sera from patients with chronic active hepatitis. They were also found, usually in low titers, in patients with other liver diseases, viral infections. some malignant diseases, heroin addiction and infertile females. Recent observations of SMA have shown that SMA activity disappears after absorption of SMA by actin, contractile protein and some types of SMA are considered to be an anti-action autoantibody (AAA). This review firstly deals with the incidence and diagnostic significance of AAA in relation to SMA. Occurences of autoantibodies to cytoskeletal proteins are also reported in sera from patients with liver diseases. The second topic is a possible role of AAA in biological studies. Moreover, localization of actin in normal cells and tissues is reported. Finally, this paper describes an induction of autoantibody to actin by immunizing rabbits with actins. A possible mechanism operating in the induction of SMA will be discussed in relation to the termination of natural tolerance to actin.