Exacerbation of myasthenia gravis after removal of a thymoma having a membrane phenotype of suppressor T cells.

We describe a case of myasthenia gravis associated with a thymoma having a membrane phenotype of suppressor T cells, as defined by monoclonal antibodies. Thymectomy resulted in exacerbation of the disease, a drastic increase in serum acetylcholine receptor-antibody titer, and a decrease of the circulating suppressor T cell population. The findings indicate that the etiopathogenic relationship between the thymus and myasthenia gravis is variable and complex.