Antiacetylcholine Receptor Antibody in Juvenile Myasthenia Gravis

Abstract

Acetylcholine receptor antibody (AchR-Ab) has been recognized to play a vital role in the pathogenesis of myasthenia gravis. In this study, we examined serum AchR-Ab levels and prognosis. Forty-three patients were followed for 7 months to 12.5 years. Patients were grouped by Fukuyama's classification; 36 patients of ocular type, 4 patients of generalized type. and 3 patients of bulbar type. Assay for AchR-Ab was performed as described by Almon (1976) using detergent-extracted acetylcholine receptor from the rat denervated muscle as antigen. Ten patients of ocular type were treated with anticholinergic drugs only.
Most of these patients had serum AchR-Ab levels lower than 0.2 pmol/ml throughout the course of our study and had no ocular symptoms for 0.8 to 7.3 years. AchR-Ab was assayed for 11 in of 36 patients with ocular type before steroid therapy. All these patients showed a reduction in AchR-Ab levels 6 months after the steroid therapy. Six of these 11 patients experienced prolonged asymptomatic periods (1.1 to 5.7 years). Three of 4 patients with generalized type revealed higher levels of AchR-Ab compared with those of ocular type. Their serum AchR-Ab levels once fell down 6 months after the steroid therapy, but their AchR-Ab levels fluctuated during treatment. Three patients of bulbar type showed a reduction in AchR-Ab following the steroid therapy.
Our results suggest that there seems to be a relationship between AchR-Ab levels and clinical severity during drug therapy.