Effect of radioactive iodine therapy on cytokine production in Graves' disease: Transient increases in interleukin-4 (IL-4), IL-6, IL-10, and tumor necrosis factor-alpha, with longer term increases in interferon-gamma production

Spontaneous and mitogen-stimulated production of interleukin-4 (IL-4), IL-6 , PIG, IL-12, interferon-gamma (IFN gamma), and tumor necrosis factor-a wer e evaluated by enzyme-linked immunospot assay of peripheral blood mononucle ar cells from patients with Graves' disease immediately before and at 4, 17 , and 59 days after treatment with radioactive iodine. Patients had signifi cantly reduced IL-4 and IFN gamma production before treatment compared with healthy controls. Both cytokines were increased to normal levels by day 17 after treatment, and IFN gamma remained at normal levels on day 59, wherea s IL-4 returned to subnormal levels at this time. IL-12 production was init ially normal and was not significantly altered by therapy. IL-6, IL-10, and tumor necrosis factor-alpha were also normal before radiotherapy, but incr eased significantly on day 17, returning to pretreatment levels by day 59. Thus, radioiodine treatment induced a transient increase in both proinflamm atory and antiinflammatory cytokines and a more prolonged increase in IFN g amma production, the latter representing a definite shift toward a type 1 c ytokine profile.