[Antigen receptor V beta gene usage of T lymphocytes in diseased thyroids in patients with autoimmune thyroid diseases]

To explore the patterns of TCR V beta gene families and the preferentially used V beta genes in intrathyroidal T lymphocytes (ITL) of patients with Graves disease and Hashimoto thyroiditis.

Thyroid tissues of 12 patients with Graves disease, and 15 patients with Hashimotos thyroiditis were used for RNA extraction. Then, the RNA was used as templates for RT-PCR with a panel of primers including 24 oligonucleotides specific for TCR V beta gene families as upstream primers and one oligonucleotide specific for C beta as downstream primer. The amplified products were subjected to electrophoresis in agarose gels and observed under UV light. The positive expression of TCR V beta gene was identified by comparing the products with the size of the designed V beta genes. The matched peripheral blood samples of 5 Graves patients, 5 Hashimoto thyroiditis patients and 7 normal subjects were also obtained and used as controls.

In 24 TCR V beta gene families tested for each individual sample, their average expressions were 5.3 +/- 1.2 and 13.4 +/- 3.0 in thyroid specimens of patients with Graves disease and Hashimoto thyroiditis, respectively, while those in the matched peripheral blood lymphocytes of the above two groups and normal controls were 23.0 +/- 1.0, 22.2 +/- 1.3 and 22.4 +/- 1.7, respectively. In addition, some of the TCR V beta genes such as V beta 3, V beta 5 and V beta 8 were more frequently used by intrathyroidal lymphocytes of Graves disease.

These data indicate the oligoclonality of the intrathyroidal T cell populations in patients with Graves disease. Also, those of the preferentially used TCR V beta genes can be regarded as molecular targets for specific immune intervention. In contrast, the loss of restriction of TCR V beta gene utilization exists in Hashimoto thyroiditis, which may be related to the recruitment of T lymphocytes in thyroid glands through this mechanism.