Thyroid infiltrating cells in juvenile autoimmune thyroiditis: a follow-up of 1 year.

The composition of the cellular infiltrate in thyroid glands of 12 patients with juvenile autoimmune thyroiditis (JAIT) was followed for a period of 1 year. The diagnosis of JAIT was based on a firm goiter and on cytologic criteria of lymphocytic thyroiditis. Samples from the thyroid gland were obtained by fine-needle aspiration biopsy three times at 6-month intervals. Lymphocytes with a few lymphoid blasts and plasma cells dominated the cellular infiltrate. The relative number of the different cell types remained unchanged during the follow-up time of 1 year. Analysis of the lymphocytes revealed that about 60% of the infiltrating lymphoid cells were T cells and about 30% expressed B-cell markers. The T helper/suppressor ratio was significantly higher in the thyroid (2.2) than in the corresponding blood sample (1.2). Practically no changes were seen in the proportions of lymphocyte subclasses either in the gland or in the blood of the patients during the follow-up. At the time of diagnosis more than half of lymphocytes in the thyroid were HLA class II positive as were most of the glandular epithelial cells. The proportion of cells expressing class II was similar in samples taken at diagnosis and 6 and 12 months later, indicating a continuous state of immunoactivation in the thyroid gland.