Decreased suppressor T-lymphocytes in autoimmune thyroid diseases detected by monoclonal antibodies.

Monoclonal antibodies reacting with cell surface antigens of helper (T4), suppressor (T8) T cells and common T-cell antigen (T3) were used by an immunofluorescence technique to enumerate peripheral T-lymphocytes in 42 patients with Graves' disease and 16 patients with Hashimoto's thyroiditis. The percentages of total T cells (cells which react with anti-T3) and helper/inducer cells (cells which react with anti-T4) among peripheral mononuclear cells in Graves' and Hashimoto's patients were not significantly different from those found in normal controls, except for a decrease in cells which react with anti-T3 in toxic Graves' disease without medication. The most important finding was a decrease in the percentage of cytotoxic/suppressor T cells (cells which react with anti-T8) in toxic Graves' disease and Hashimoto's thyroiditis. In patients with Graves' disease who were hyperthyroid or euthyroid on propylthiouracil treatment and euthyroid after radioactive iodide treatment, the percentage of cells which react with anti-T8 was also decreased, but this did not reach statistical significance. These findings support the hypothesis of defects in suppressor T-lymphocytes in autoimmune thyroid diseases.