Activated interstitial and intraepithelial thyroid lymphocytes in autoimmune thyroid disease.

This study has further characterised the thyroid lymphocytic infiltrate in Graves' disease and Hashimoto's thyroiditis. Two population of lymphocytes were identified. The interstitial population occurred as a diffuse and a focal infiltrate; most cells were CD3-positive (T cells) and in 4 of 6 glands CD8 (suppressor-cytotoxic)-positive T cells predominated. The intraepithelial population was CD3-negative, CD8-positive. Both populations also contained a few NK (Leu 11b positive cells) in some glands. Many of the lymphocytes in both populations stained with UCHL1 and RFT2 suggesting that these are primed and activated cells, borne out by staining for transferrin receptor expression. Although thyroid follicular cells were Ia-positive, macrophages and dendritic cells were found in all cases, so that a role for antigen-presentation by all three potential candidates in autoimmune thyroiditis is possible.