Reversible thyroid dysfunction during treatment with GM-CSF.

To investigate whether autoimmunity against thyroid antigens is induced or exacerbated by granulocyte-macrophage colony-stimulating factor, thyroid function and thyroid autoantibodies were studied in 14 patients with advanced breast cancer and 11 with soft-tissue sarcoma who received several cycles of doxorubicin and cyclophosphamide plus GM-CSF 250 micrograms/m2 intravenously daily for 10 days in every 21 day cycle. All patients had normal thyroid function before treatment. In 2 patients with pre-existing thyroid antibodies, thyroid dysfunction developed but disappeared after cessation of GM-CSF. No other autoimmune abnormalities appeared. Stimulation of antigen-presenting cells by GM-CSF may bring about this phenomenon.