SEMIQUANTITATIVE ANALYSIS OF INTERLEUKIN-1-ALPHA, INTERLEUKIN-6 AND INTERLEUKIN-8 MESSENGER-RNA EXPRESSION BY HUMAN THYROCYTES

It has been suggested that the thyroid itself may contribute to the in flammatory process observed in autoimmune thyroiditis by releasing the cytokines interleukin-1 alpha (IL-1 alpha), interleukin-6 (IL-6) and interleukin-8 (IL-8), but studies of cytokine gene expression in thyro cytes have been limited and conflicting. A semi-quantitative reverse t ranscription-PCR technique has been used to investigate the expression of IL-1 alpha, IL-6 and IL-8 mRNA in the human thyroid cell line HTor i3 and in cultures of primary human thyroid follicular cells (TFCs). C ytokine mRNA levels were examined over a 24-h period, and the modulato ry effects of exogenous IL-1 alpha, interferon-gamma (IFN-gamma) and T SH investigated. Basal expression of IL-1 alpha, IL-6 and IL-8 mRNA wa s detected in HTori3 and primary TFC cultures. Stimulation with IL-1 ( 10 U/ml) for 12 h produced an increase in the level of IL-1 alpha mRNA in both primary TFC and HTori3 cultures. IL-6 and IL-8 mRNA levels we re increased by the addition of IL-1 in both cell types, and this effe ct was detected throughout the 24-h time-course. IFN-gamma (100 U/ml) had no significant effect on cytokine gene expression. A higher concen tration of IFN-gamma (500 U/ml) had no significant effect on the expre ssion of IL-1 alpha or IL-8 but produced an increase in the level of I L-6 mRNA in primary cultures and in HTori3 cells. Addition of TSH (1 m U/ml) produced an increase in the level of IL-1 alpha mRNA in primary TFC and HTori3 cells, at 12 and 24 h. TSH had no significant effect on the expression of IL-6 or IL-8 mRNA. These results demonstrate that h uman TFCs constitutively express IL-1 alpha, IL-6 and IL-8 mRNA and th at this expression can be modulated by IL-1, IFN-gamma and TSH.