[Hashimoto's thyroiditis and HLA in Caucasian Italians]

Sixty cases of goitrous Hashimoto's thyroiditis were observed at the first diagnosis. For 18 of the cases, the diagnosis was made only on the basis of cytological examination since antithyroid antibodies were always negative. To determine if seronegative or seropositive forms constituted a particular genetically determined subgroup, we evaluated whether such peculiarities were related to specific HLA haplotype. Analysis of HLA antigens showed in the seropositive a significant increase in the frequency of HLA-B51 and HLA-A2, a significant decrease in the frequency of HLA-A1 and HLA-DR1. In seronegative cases no increase was found in the frequency of HLA-A-B-DR antigens, but they showed a strong positive association with HLA-DQ3. Our results show that association of Hashimoto's thyroiditis with HLA antigens was different in seronegative and seropositive subgroup. This finding would seem to support the hypothesis that in a few subjects the entire immune process develops exclusively within the involved organ and this process would be genetically determined.