Influence of interleukin 1 and antihuman interleukin 1 receptor antibody on the growth and function of the thyroid gland in rats

Abstract

Cytokines seem to influence the hypothalamo-pituitary-thyroid axis. We have studied the effect of different doses of interleukin 1 alpha (IL-1 alpha) and IL-1 beta (given twice daily ip) alone or together with antihuman IL-1 receptor antibody (aIL-1ra) on the proliferation of thyroid follicular cells and thyroid hormone levels in male Wistar rats. We have examined the influence of IL-1 alpha and IL-1 beta at doses of 10.0, 1.0 and 0.1 micrograms/kg body wt of animal and aIL-1ra at a dose of 10.0 micrograms/kg body wt of animals. The incorporation of bromodeoxyuridine into thyroid follicular cell nuclei was used as an index of cell proliferation (labeling index: LI) and measured 24 h after the last of two injections of interleukin. Interleukin 1 beta, at all examined doses, increased thyroid follicular cell proliferation when compared to controls (p < 0.05), and a positive correlation between log of the dose of IL-1 beta used and LI (r = 0.62, p < 0.05) using Student's t-test was found. The administration of aIL-1ra alone also enhanced the thyroid follicular cell proliferation, whereas aIL-1ra used together with IL-1 beta exerted a less pronounced effect than each of these substances used separately (p < 0.05). Interleukin 1 alpha at the dose of 10.0 micrograms/kg body wt increased the proliferation of thyroid follicular cells (p < 0.05). Thyroid hormone levels did not change in any of the experiments. These results suggest a regulatory role of IL-1 upon the proliferation of thyroid cells.