Supplementary Material for: Interactions of Lymphocytes, Thyrocytes and Fibroblasts in Hashimoto’s Thyroiditis: An Immunohistochemical and Ultrastructural Study

Background: The mechanism of autoimmune reaction, a diffuse process consisting of a combination of epithelial cell destruction, lymphoid cellular infiltration, and fibrosis in Hashimoto’s thyroiditis, is not well known. The aim of this study was to analyse the cell subsets in thyroid tissue of patients with Hashimoto’s thyroiditis. Methods: We studied paraffin-embedded thyroid specimens obtained from children with Hashimoto’s thyroiditis and children without an autoimmune thyroid disease. Mononuclear T cells were detected by means of CD3+, CD4+, CD8+ antibodies, B cells by CD79 alpha+ antibodies, and antigen-presenting cells by CD1a+ antibodies, and they were counted in every 1,000 cells. The specimens from each patient were routinely estimated and investigated under the electron microscope. Results: In Hashimoto’s thyroiditis, we observed a statistically significant increase in T suppressor/cytotoxic cells CD8+ (20.54 ± 0.68%) in comparison to the control group (0.65 ± 0.30%), simple goitre (4.01 ± 5.54%) and nodular goitre (8.53 ± 2.37%), and a statistically significant increase in plasma CD79 alpha+ cells (31.65 ± 9.11%) in comparison to the control group (4.11 ± 1.94%), simple goitre (1.83 ± 0.64%) and nodular goitre (5.22 ± 1.63%). Simultaneously, we observed a low number of CD4+ T helper cells in the thyroid gland (0.93 ± 0.99%) in Hashimoto’s thyroiditis (0.19 ± 0.05% in the control group, 1.05 ± 2.71% in simple goitre, 2.03 ± 1.06% in nodular goitre). The ultrastructural investigations showed interactions between T cells, plasmocytes, fibrocytes and thyrocytes leading to apoptosis of thyrocytes. An immunological synapse between T cells, plasmocytes and thyrocytes in the thyroid gland was noticed. Conclusions: In Hashimoto’s thyroiditis, autoantigen presentation in combination with a low number of CD4+ T helper cells and a high number of CD8+ cells and plasmocytes caused the development of a cytotoxic reaction against thyrocytes, leading to apoptosis of the thyrocytes.背景：桥本甲状腺炎（Hashimoto’s thyroiditis）是一种以上皮细胞破坏、淋巴细胞浸润及纤维化为特征的弥漫性自身免疫反应过程，但其具体发病机制尚未完全阐明。本研究旨在分析桥本甲状腺炎患者甲状腺组织中的细胞亚群。 方法：本研究纳入了来自桥本甲状腺炎患儿与非自身免疫性甲状腺疾病患儿的石蜡包埋甲状腺标本。采用CD3+、CD4+、CD8+抗体检测单核T细胞，以CD79α+抗体标记B细胞，以CD1a+抗体标记抗原呈递细胞，并对每1000个细胞中的各类细胞进行计数。所有患者标本均经常规处理后，在电子显微镜下进行观察分析。 结果：与对照组（0.65±0.30%）、单纯性甲状腺肿组（4.01±5.54%）及结节性甲状腺肿组（8.53±2.37%）相比，桥本甲状腺炎患者的CD8+ T抑制/细胞毒性细胞比例（20.54±0.68%）具有统计学意义的显著升高；同时，其甲状腺组织内CD79α+浆细胞比例（31.65±9.11%）亦显著高于对照组（4.11±1.94%）、单纯性甲状腺肿组（1.83±0.64%）及结节性甲状腺肿组（5.22±1.63%）。此外，桥本甲状腺炎患者甲状腺组织中的CD4+ T辅助细胞比例较低（0.93±0.99%），而对照组为0.19±0.05%、单纯性甲状腺肿组为1.05±2.71%、结节性甲状腺肿组为2.03±1.06%。超微结构观察显示，T细胞、浆细胞、纤维细胞与甲状腺滤泡上皮细胞之间存在相互作用，可导致甲状腺滤泡上皮细胞凋亡；同时观察到甲状腺组织内T细胞、浆细胞与甲状腺滤泡上皮细胞之间形成了免疫突触。 结论：桥本甲状腺炎中，自身抗原呈递联合CD4+ T辅助细胞数量减少、CD8+ T细胞及浆细胞数量升高，共同介导了针对甲状腺滤泡上皮细胞的细胞毒性反应，最终导致甲状腺滤泡上皮细胞凋亡。