The effect of anti-thymocyte antiserum in progressive myasthenia gravis.

The therapeutic effect of goat anti-human thymocyte antiserum globulin (ATG) was assessed in ten patients with myasthenia gravis. Five patients had undergone prior thymectomy. All subjects had far-advanced, debilitating and progressing disease poorly responsive to classic anticholinesterase therapy. Prolonged, low dose ATG therapy was used with 1.0-2.6 grams/protein administered intramuscularly over a 28-73 period. Depression of cellular immunity was observed with anti-thymocyte antiserum was more profound in patients with a prior thymectomy. Therapeutic responses of varying degrees were noted in 8 out of 10 patients. Completion of a course of ATG and discontinuation of the drug did not lead to acute relapse states. Follow-up examinations for over five years have been maintained. A mean remission period of approximately two years was observed. It is suggested that this therapy deserves further evaluation. Subjects with prior thymectomy and progressive disease may represent the most ideal candidates.