The effect of thymectomy on autoreactive T- and B-lymphocytes in myasthenia gravis

Eleven patients with myasthenia gravis were followed for three years after thymectomy. Acetylcholine receptor-specific T-cell stimulation was found in 8/11 patients before operation as compared to 2/11 three years after thymectomy. Changes of T-cell antireceptor-reactivity were commonly paralleled by changes in disease severity. The numbers of cells secreting IL-2 upon stimulation with human acetylcholine receptor correlated with those secreting IFN-gamma. T-cell reactivity against a monoclonal acetylcholine receptor antibody did not decrease after thymectomy. Such reactivity could reflect a beneficial immune response counteracting anti-receptor reactivity. The frequency of autoantibody-secreting cells remained unchanged, while the serum concentration of acetylcholine receptor antibodies started to decrease one year after thymectomy. All examined thymus-cell suspensions contained autoreactive T- and B-lymphocytes. There was a preferential enrichment of autoreactive lymphocytes in the thymus in a few patients with recent onset of disease.