Circulating lymphocyte subpopulations in Hashimoto thyroiditis

Abstract

Peripheral blood and T and B lymphocytes and [¹²⁵I]thyroglobulin-binding lymphocytes were investigated in twenty-two euthyroid Hashimoto thyroiditis patients and in twenty-two age- and sex-matched normal subjects. Although the total lymphocyte count in Hashimoto patients (mean±SEM = 1226±187/mm³) was lower than in normal subjects (1603±156/mm³) this difference was not statistically significant. There was, however, a statistically significant reduction in the proportion of circulating T lymphocytes in the Hashimoto patients (mean±SEM = 57·4±2·5%) as assessed by the sheep red-cell rosette method when compared with the normal controls (mean±SEM = 66·7±1·8%). The proportion of B lymphocytes in the peripheral blood as assessed by indirect immunofluorescence, was not significantly different being 21·6±2·1% in the Hashimoto patients and 20·2±1·1% in normal subjects.

[¹²⁵I]thyroglobulin-binding lymphocytes, as assessed by autoradiography were present in the circulation of nineteen Hashimoto patients with a mean frequency of 8·37±1·15/10⁴ lymphocytes and in thirteen normal subjects with a mean of 8·84±0·93/10⁴ lymphocytes. There was no difference in the degree of [¹²⁵I]thyroglobulin binding between the two groups as determined by grain count analysis. There was no apparent correlation between age or thyroglobulin antibody titres and the frequency of [¹²⁵I]thyroglobulin-binding lymphocytes. Thyroglobulin-binding lymphocytes were increased 100-fold in a Hashimoto thyroid biopsy in comparison to the patient's peripheral blood.