IDENTIFICATION OF 2 SERUM COMPONENTS REGULATING THE EXPRESSION OF LYMPHOCYTE-T FUNCTION IN CHILDHOOD MYASTHENIA-GRAVIS

We studied serums and cells from nine children with myasthenia gravis to determine whether there were alterations in the distribution or function of different T-lymphocyte subpopulations. The low numbers of E-rosette-forming T lymphocytes and their failure to respond to antigen by producing normal suppressor T cells were correlated with the presence of an IgG antibody directed toward the theophylline sensitive T-cell subset; this activity could be blocked by d-tubocurarine. Incubation of normal T lymphocytes with serum from patients rendered the cells “myasthenia-like” when assayed for E-rosettes and for antigen-induced suppressor-cell function. A second, non-IgG factor found in patients’ serums had activity like that of thymic hormone and induced T-cell maturation in normal bone marrow. This factor was not inhibited by d-tubocurarine; its activity was strongest in the two patients most severely affected, and it disappeared after thymectomy in both these patients. We conclude that in childhood myasthenia gravis there may be two independent serum factors; one an IgG antibody directed at a subset of T lymphocytes, blocked by d-tubocurarine and apparently unaffected by thymectomy, and the other a thymus factor that induces T-lymphocyte maturation. (N Engl J Med 301:625–629, 1979) MYASTHENIA gravis is a specific autoimmune disease affecting nicotinic acetylcholine receptors of the neuromuscular junction and resulting in weakness and muscle fatigue.1 In approximately 90 per cent of adult patients with this disease, serum IgG antibody against acetylcholine receptors has been found.2 This antibody leads to accelerated degradation of the receptor and may also result in blockade of the binding site of the receptor molecule.2 3 4 5 6 Experimental autoimmune myasthenia gravis has been produced in several animal models, and antibodies to the acetylcholine receptor have been demonstrated after immunization induced by exogenous acetylcholine receptor.7 In rats, the course of the disease is. © 1979, Massachusetts Medical Society. All rights reserved.