Immunohistochemical study of myoglobin in neuromuscular diseases.

The localization of myoglobin (Mb) in skeletal muscle in various neuromuscular diseases was studied by an immunoperoxidase technique. The immunoreactivity of Mb was shown to be well preserved in muscle fibers that showed denervation atrophy or vacuolar degeneration, as well as in muscle fibers with apparently normal structure. Marked decrease or loss of Mb immunoreactivity was observed in muscle fibers with hyaline degeneration or floccular necrosis, where there was irreversible disruption of the muscle fibers. On the other hand, regenerated fibers showed variable immunostaining for Mb. Most regenerated fibers showed little or no immunostaining but some showed staining as strong as apparently normal fibers. These findings in various neuromuscular diseases suggested that the elevation of serum Mb in patients with these diseases was ascribed to its release from severely injured, necrotic muscle fibers. The immunohistochemistry for Mb was shown to be useful to evaluate plasma membrane injury and characterize muscle degeneration.