Accumulation of thyroid antigen-reactive T lymphocytes in the gland of patients with subacute thyroiditis.

Blood and thyroid-infiltrating lymphocytes from patients with de Quervain's subacute thyroiditis were tested in the leucocyte migration inhibition test for cell-mediated immunity (CMI) to thyroid antigen. Blood leucocytes were positive for CMI in eleven out of thirteen (85%) patients in the acute phase of the disease. In five cases tested repeatedly this reactivity disappeared after 7-11 months. Thyroid-infiltrating lymphocytes were obtained from eight patients by fine-needle aspiration biopsy. There was a relative accumulation of T lymphocytes (90 +/- 5%) in the thyroid gland as compared to lower numbers of T cells (65 +/- 5%) in the blood. When thyroid-infiltrating lymphocytes were tested for CMI to thyroid antigen, a significantly stronger inhibition was demonstrated with the infiltrating lymphocytes as compared to that of blood leucocytes. We conclude that thyroid antigen-reactive T cells accumulate in the glands of patients with subacute thyroiditis. This observation is in accordance with the presumed viral aetiology of this disorder.