Interleukin 2-Activated Killer Cells Do Not Mediate Autologous Thyrocyte Lysis in Autoimmune Thyroid Disease In Vitro

Abstract

Because of interest in IL-2, and IL-2-activated killer cell-induced hypothyroidism in humans, we attempted to study an in vitro system that might prove to illuminate this disorder. We have thus studied interleukin 2 (IL-2--0, 12.5, 25, or 50 U/mL) activated killer cell-mediated autologous thyrocyte lysis, as well as cytotoxic activity in IL-2-stimulated mononuclear cell supernatants in 7 patients with autoimmune thyroid disease (2 Graves' disease and 5 Hashimoto's thyroiditis) using the 51Cr release assay. Controls included 14 patients with nonautoimmune thyroid disease (3 nontoxic goiter, 8 follicular thyroid adenoma, 2 papillary thyroid carcinoma, and 1 medullary carcinoma of the thyroid). Soluble IL-2 receptor (sIL-2R) in supernatants of peripheral mononuclear cells stimulated by IL-2 from these patients also was measured. Whereas in the control preparations, IL-2-activated killer cell activity was increased in a dose-dependent fashion relative to the IL-2 concentration, as well as to the effector cell/target cell ratio, in preparations from patients with autoimmune thyroid disease, this activity was not elevated as the IL-2 concentration was increased. The susceptibility of thyrocytes to the lytic effect of IL-2-activated killer cells was higher in controls than that in autoimmune thyroid disease (at concentrations of IL-2 of 0, 12.5, 25, and 50 U/mL) (p less than 0.01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)