Context: Follicular helper T (Tfh) cells exert an important role in the autoimmune diseases.
Aim: Our study aimed to explore the role of Tfh cells in patients with autoimmune thyroid disease (AITD).
Design: Tfh cell is a new subset regulating the antibody production of B cell. Previous studies implicated CD4+CXCR5+ICOShigh or CD4+CXCR5+PD-1high as the markers of circulating Tfh cells. Sixty-five patients with AITD and 30 healthy controls were enrolled in the current study. The percentages of circulating Tfh cells were assessed by flow cytometry. The correlation between the percentages of CD4+CXCR5+ICOShigh T cells and the levels of autoantibodies or hormones was also analyzed. Additionally, polyphasic methods were applied to investigate the status of Tfh cells in thyroid glands of Hashimoto's thyroiditis patients.
Results: Increased percentages of circulating Tfh cells in AITD patients were detected, and a positive correlation between the percentages of circulating Tfh cells and the serum concentrations of anti-TSH receptor-Ab/thyroperoxidase-Ab/thyroglobulin-Ab was confirmed. A positive or modest relationship between the percentages of circulating Tfh cells and serum free T3 or free T4 was revealed in Graves' disease patients. Additionally, follow-up analysis indicated that in some Graves' disease patients the percentage of circulating Tfh cells decreased after treatment. Furthermore, a certain number of CD4+CXCR5+ICOShigh T cells together with enhanced expression of IL-21 and Bcl-6 mRNA were detected in thyroid tissues from Hashimoto's thyroiditis patients.
Conclusion: The current study discovered an increased frequency of Tfh cells in AITD patients, which implies that this cell subset might play an important role in the pathogenesis of AITD.