Objective: 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.
Methods: 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.
Results: 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.
Conclusions: 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.