Cells infiltrating the thyroid in juvenile autoimmune thyroiditis.

Cell samples derived from the thyroid glands of twelve children with juvenile autoimmune thyroiditis (JAIT) were analysed. The cytological findings were those of chronic lymphocytic thyroiditis in eight and suggestive of that disease in four patients. About 86% of the cells infiltrating the thyroid were lymphocytes, 4% were lymphoid blasts, 6% neutrophils and 3% monocytes. Analysis using monoclonal antibodies showed that about 60% of the lymphocytes were T cells and half of the lymphocytes expressed HLA Class II-antigens. T helper cells dominated with a T helper/suppressor ratio of 2.2 in thyroid while the ratio was 1.2 in peripheral blood. Of the thyroid epithelial cells, 80% also expressed HLA class II. The immune activation and immunoglobulin synthesis within the thyroid are discussed.