We here report for the first time that both antigens, TPO and Tg, are recognized by CD8-positive T cells and are involved in the thyroid destruction process leading to clinical disease manifestation.

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tive expression 12,57 in HT vs. 19.40 in control group (CG), p = 0.0002; 12,10 in GD vs. 19.40 in CG, p = 0.0002) and in CD8 + -T-cells (13.13 in HT vs. 18,12 in CG, p = 0.02; 11.66 in GD vs. 18.12 in CG, p = 0.0002). GD and HT showed signifi cantly decreased miRNA 155_2 and miRNA 155*_1 in HT in CD8 + -T-cells (10.69 in HT vs. 11.30 in CG, p = 0.01; 10.40 in GD vs. 11.30 in CG, p = 0.005). This study confi rms signifi cant variations of miRNA200a and miRNA155 in patients suffering from GD and HT in vivo in CD4 + T-cells and CD8 + T-cells. These data may help to better understand the gene regulations in the causative cells causing these autoimmune processes. They extend our very limited knowledge concerning miRNAs in thyroid diseases. Abstract ▼Graves' disease (GD) and Hashimoto's thyroiditis (HT) are the most common autoimmune thyroid diseases (AITD). MicroRNAs (miRNAs) critically control gene-expression and play an important role in regulating the immune response. The aim of this study was to prove signifi cant variations of key immunoregulatory miRNAs in peripheral blood mononuclear cells (PBMCs) and in CD4 + and CD 8 + T-cells of AITD patients. Selected miRNAs were amplifi ed by a semiquantitative SYBR Green PCR from PBMCs and purifi ed CD4 + and CD 8 + T-cells of 59 patients with GD, HT, and healthy controls. Both GD and HT showed signifi cantly decreased miRNA 200a_1 and miRNA 200a2* in CD4 + -T-cells (mean rela-

Graves' disease (GD) and Hashimoto's thyroiditis (HT) are the most common autoimmune thyroid diseases (AITDs) affecting up to 5% of the general population. In Caucasians HT has a prevalence of up to 4.60% and GD a prevalence of 1-2%. The aim of this study was to investigate the association between HLA-A2 and the AITDs GD and HT among Caucasians. HLA alleles of 33 patients with GD and 75 patients with HT were determined by serological typing. The frequency of HLA A2 was significantly reduced in GD (p=0.033) but not in HT (p=n.s.) as compared to control samples. In individuals positive for HLA-A2 odds ratio for protection from GD was found to be 2.8. This study supports the hypothesis that genetic predisposition to GD is not restricted to MHC class II molecules. The significant negative association between HLA A2 and GD supports the hypothesis that MHC class I genes may be relevant for the protection from GD. In contrast the nonsignificant results for HT indicate that this association may not apply to AITDs in general.