Characterization of lymphoid cells in the thyroid of patients with Graves' disease.

The distribution and function of lymphoid cells has been investigated in thyroid glands obtained at operation from 16 patients with Graves' disease (GD) using a peroxidase technique to enumerate total T and B lymphocytes as well as helper and suppressor T cell subsets in tissue sections. A spectrum of lymphocytic infiltration was observed and the increase from minimal numbers of immune cells in some GD thyroids to focal thyroiditis in others appeared to be due to a rise in all the lymphoid cell types analysed and was not the result of major change in any one lymphoid compartment. T cells were diffusely distributed whereas B cells tended to occur in aggregates. Small numbers of OKT6+ cells (possibly antigen presenting cells) were observed although these were less numerous than in lymphoid organs such as tonsil. Lymphoid cell suspensions prepared from the thyroid tissue of five of seven GD individuals treated pre-operatively with propranolol synthesized thyroid autoantibodies spontaneously in culture and this synthesis was decreased in the presence of pokeweed mitogen. Since the OKT8+ T cell subset has been shown to suppress immunoglobulin production by lymphocyte cultures containing mitogen, it appears that the suppressor T cells, which are readily demonstrable in GD thyroid sections, are functional. It seems unlikely, therefore, that a defect in this type of suppression is responsible for the initiation or perpetuation of the autoimmune response to thyroid antigens in GD.