Cytokines are an extraordinarily diverse group of molecules, with plei
otropic and often overlapping effects. They are crucial to the autoimm
une response, and, in particular, regulation of CD4(+) and CD8(+) T-ce
ll function depends on the balance of cytokines produced during an imm
une response. It is also now clear that cytokines are produced by a wi
de array of cells, including the thyroid follicular cells (TFCs). Intr
athyroidal lymphocytes produce a heterogeneous pattern of cytokines an
d we have summarized the likely effects of these. In Graves' disease,
TFCs can themselves express immunologically important molecules as the
result of cytokine stimulation and these could contribute to the perp
etuation of the autoimmune process. In addition, cytokines have a numb
er of generally inhibitory effects on thyroid hormone production which
would tend to counter the stimulatory effects of thyroid-stimulating
hormone receptor antibodies in Graves' disease.