The Skeletal Muscle Binding Site of Antistriated Muscle Antibody in Myasthenia Gravis: An Electron Microscopic Immunohistochemical Study Using Peroxidase Conjugated Antibody Fragments

Abstract

The skeletal muscle-binding site of antistriated muscle antibody (ASMAb) from individuals with myasthenia gravis (MG) was established ultrastructurally by means of an indirect immunohistochemical technique with purified sheep antihuman IgG (PSAHG) conjugated to horseradish peroxidase (HRP). Penetration of the HRP-antibody conjugate was greatly enhanced by preparing fragments, the Fab or F(ab′)₂ of the PSAHG before HRP conjugation. ASMAb from nine patients with MG localized to the sarcoplasmic reticulum surrounding the I-band. No binding with the myofilaments could be demonstrated.