The inhibitory effect of interleukin (IL)-1 on thyroid cell functions, including cAMP and thyroglobulin production, is well documented. Recently, IL-1 was shown to enhance the production of IL-6 from thyrocytes, and IL-1 receptors were demonstrated on normal thyroid cells. The origin of IL-1 could be from infiltrating monocytes/-macrophages, endothelial cells as well as from the thyrocytes themselves. Thus, IL-1 activated thyrocyte may participate directly in the immunological process by reacting to and producing immunoinflammatory cytokines.