What are antistrial antibodies and when is testing indicated?

Striational (striated muscle) antibodies are antibodies reactive with cross-striations of skeletal muscle. Myosin, actin and a-actinin have been identified as antigens recognized by the antistrial antibodies. In human patients, such antibodies are a useful serological marker of thmoma with or without myasthenia gravis. They are rarely found in other diseases, except in those treated with D-penicillamine or allogeneic bone marrow (Cikes et al, 1988). Their pathological significance, if any, is not known, but striational autoantibodies have proven to be a useful serologic marker of thymoma. In the figure below, serum from a dog with histologically proven thymoma was incubated with normal canine muscle followed by anti-dog IgG with a fluorescent tag, then evaluated by fluorescence microscopy. Antistrial antibodies were detected at dilutions up to 1:10,000. Control tissue was incubated with normal dog serum (without thymoma) for comparison. As in human patients, detection of antistrial antibodies should be a useful marker in dogs with thymoma.