EVIDENCE FOR IMMUNOLOGICAL CROSS-REACTIVITY BETWEEN SMOOTH AND SKELETAL-MUSCLE

  • 1 January 1977
    • journal article
    • research article
    • Vol. 27  (2) , 269-272
Abstract
Selected sera of humans with high titer antismooth muscle antibodies [anti-SMA] which react with antigens which appear specific for either smooth or striated muscle, and additional sera which react with antigens which appear common to both smooth and striated muscle are described. Immunization of rabbits with skeletal muscle contractile protein provided further evidence for such cross reactivity. There are antigens in smooth muscle and skeletal muscle which will react with the same antibody. By immunofluorescence this antibody gives smooth staining with smooth muscle and striational staining with skeletal muscle. Recently Fairfax and Doniach (1976) showed cross reactivity between skeletal, smooth and cardiac muscle, but these authors were dealing with antibodies which produced diffuse rather than striational staining. The implications arising from the demonstration of cross reactivity between contractile proteins of smooth and skeletal muscle appear numerous. Attempts to identify by immunological methods smooth muscle contractile protein in various non-muscle and neoplastic cells should take account of the possiblity of the reactivity of skeletal muscle contractile protein with SMA. The multiple factors which appear to lead to the induction of smooth muscle antibody might be reviewed considering the possibility that at least some of these antibodies may be cross reactive with skeletal muscle. Concepts of the structure of skeletal and smooth muscle might be reconsidered with the view that at least one of the contractile protein components may share similar antigenic determinants. The present work demonstrated the presence of antigenic cross reactivity between smooth and skeletal muscle, it also confirmed the occurrence of antibodies reacting with one but not with the other. Such antibodies could be reactive with complex conformational determinants rather than simply with determinants unique to either smooth or skeletal muscle proteins. In terms of clinical diagnosis it may be significant that patients with a thymoma had skeletal-muscle-specific antibodies with or without separate antibodies reactive with smooth muscle. By contrast, patients with SMA and miscellaneous diagnoses may have smooth-muscle-specific or cross reactive antibodies but were not found to have skeletal-muscle-specific antibodies.