INTRATHYROIDAL CYTOKINE GENE-EXPRESSION IN HASHIMOTOS-THYROIDITIS

Hashimoto's thyroiditis (HT) is an organ-specific autoimmune disease i n which cytokines are likely to have a role in the initiation and perp etuation of the disease. Using the reverse transcription-polymerase ch ain reaction (RT-PCR) we analysed the cytokine profile in four HT tiss ue samples. Furthermore, cell fractionation was carried out on two tis sue samples and cytokine profile was studied in CD4(+) and CD8(+) T ce lls, in addition to the residual cellular infiltrate composed of CD4(- ) and CD8(-) cells. Our results showed IL-1 beta, IL-4 and IL-6 mRNA e xpression in three out of four tissue samples, whereas IL-1 alpha, IL- 2, IL-8, IL-10, interferon-gamma (IFN-gamma) and tumour necrosis facto r-alpha (TNF-alpha) were expressed in all tissue samples studied. Expr ession of IL-1 alpha and IL-1 beta was absent in both CD4(+) and CD8() subsets. However, IL-2, IL-4, IL-6, IL-8, IFN-gamma and TNF-alpha mR NA were detected in both CD4(+) and CD8(+) subsets. IL-10 was expresse d in the CD4(+) subset in one sample, whereas it was negative in both CD8(+) fractions. All the cytokines studied were expressed in the resi dual infiltrate. These results suggest a mixed Th1 and Th2 response in HT, both of which may have an important role in the pathophysiology o f the thyroid destructive process through cell-mediated cytotoxicity, and/or humoral autoimmunity manifested by autoantibody production.