Distribution of lymphocyte subpopulations in thyroid glands of human autoimmune thyroid disease

The autoimmune thyroid disease (AITD) is an organ-specific autoimmune disease characterized by the breakdown of self-tolerance to thyroid antigens. Some lymphocytes have been identified to be related notably to the pathogenesis of AITD. This article evaluated the distribution of the lymphocytic subpopulation in thyroid glands in order to develop the immunospecific forms of therapy for AITD.

Damaged thyroid specimens were obtained from 18 Graves' disease (GD) and 17 Hashimoto's thyroiditis (HT) patients. Normal thyroid specimens were obtained from unaffected glands of 17 patients who underwent parathyroidectomy. We evaluated the distribution of lymphocytic subpopulation by analyzing the expression difference and correlationship among CD4+ T lymphocyte, CD8+ T lymphocyte, CD20+ B lymphocyte as well as regulatory T cells(Tregs)' marker FoxP3 in the thyroid tissues via immunohistochemistry.

Our research uncovered that no distinct lymphocyte infiltrated in the normal thyroid specimens. Scarcely any lymphocyte infiltration could be found in half of the totally 18 GD thyroid specimens. For the rest 9 GD specimens, CD8+ T cells and CD20+ B cells were expressed more or less in all of them, FoxP3+ Tregs were detected in 7 of them and CD4+ T cells were weakly expressed in only 2 of them. For the 17 HT thyroid specimens, CD20+ B cells were stained strongly in all of them, CD4+, CD8+ T cells were expressed more or less in most of them and FoxP3+ Tregs could be detected in 9 of them.

Based on CD20+ B cells predominantly infiltrating in all HT thyroid tissues we suggested CD20 antibody might be of help for HT treatment. Furthermore based on FoxP3+ Tregs abundantly infiltrating in some of the AITD thyroid specimens, we considered that activating the Tregs' function in comparison to increasing the Tregs' number only, may be a more effective approach to the treatment of AITD in some cases.