Serial analysis of the effects of methimazole or radical therapy on circulating CD16/56 subpopulations in Graves' disease.

The distribution of peripheral blood CD16/56 cytotoxic T and natural killer (NK) cells in Graves' disease patients is analyzed in order to correlate them with disease activity and with prognosis. Eighteen patients with Graves' disease, twenty-four patients with Hashimoto's thyroiditis and thirty-two sex- and age-matched healthy control subjects were studied. Peripheral blood CD16/56 (cytotoxic T and NK) cells were analyzed by cytofluorometry. A decreased proportion of CD16/56+ and CD16/ 56+CD3+ cells were detected in Graves' disease patients when compared with thyroiditis patients and healthy control groups. No correlation was detected with serum free thyroxine. On diagnosis, patients who would require a radical treatment for thyrotoxicosis control showed a significant decrease of cytotoxic CD56+ T (CD3+) and NK (CD3-) cells compared with those who would maintain the euthyroid state after methimazole. These results suggest that the cytotoxic compartment, both T and NK cells, of the immune system is altered in patients with Graves' disease, independently of the functional thyroid status. Changes in peripheral blood lymphocytes in Graves' disease patients could be useful as predictive markers of an unfavorable outcome.