[An immunohistochemical study on human leucocyte antigen-DR in Hashimoto thyroiditis and Graves disease]

By using anti-human leucocyte antigen (HLA)-DR antibodies with the help of avidin-biotin complex immunohistochemical method, the authors studied the number and distribution of HLA-DR positive thyroid cells in thyroid glands from sixteen patients with Hashimoto thyroiditis, fourteen patients with Graves disease, and six controls. The correlation between the degree of thyroid cells HLA-DR expression and the values of serum thyroglobulin antibodies and thyroid peroxidase antibodies determined with radioimmunoassay was also analyzed in order to find the relation of aberrant HLA-DR expression on thyroid cells with thyroid autoimmune reaction. Normal thyroid cells did not express HLA-DR antigens, but HLA-DR antigens were often found in some thyroid cells from patients with Hashimoto thyroiditis or with Graves disease. The number of HLA-DR positive thyroid cells was significantly greater in Hashimoto thyroiditis than in Graves disease. HLA-DR positive thyroid cells were localized in areas harbouring infiltrating lymphocytes. The degree of thyroid HLA-DR expression correlated closely with the values of serum thyroglobulin antibodies and thyroid peroxidase antibodies in Hashimoto thyroiditis and Graves disease. These results suggest that infiltrating lymphocytes may facilitate HLA-DR expression on thyrocytes. The occurrence of serum thyroglobulin antibodies and thyroid peroxidase antibodies in Hashimoto thyroiditis and Graves disease may have a close relationship with aberrant HLA-DR expression by thyrocytes which were apt to be damaged by autoimmune attack.