Allergen immunotherapy improves defective follicular regulatory T cells in patients with allergic rhinitis.

BACKGROUND: The function of follicular regulatory T (TFR) cells, especially in regulating IgE production in patients with allergic diseases, is poorly understood. OBJECTIVE: We sought to investigate the phenotype, function, and clinical relevance of TFR cells in patients with allergic rhinitis (AR). METHODS: The phenotype and frequency of tonsillar and circulating TFR cells were characterized by using flow cytometry. TFR cell function was examined in an assay by coculturing with follicular helper T cells and B cells. The associations between TFR cells and the clinical features in patients with AR before and after allergen immunotherapy (AIT) were analyzed. RESULTS: TFR cells were detected in germinal centers of tonsils, but compared with subjects without AR, the frequencies decreased in patients with AR who were allergic to house dust mites. Circulating TFR cells in blood were phenotypically and numerically correlated with tonsillar TFR cells, and a reduction of circulating TFR cells but not total or CXCR5- regulatory T cells was noted in patients with AR compared with healthy control subjects. Moreover, circulating TFR cells in patients with AR showed a specific defect in suppressing IgE production but were capable of suppressing production of other immunoglobulin types. We identified negative associations of circulating TFR cell frequencies and function with antigen-specific IgE levels or disease severity in patients with AR. After AIT, the frequencies and function of circulating TFR cells were improved, which positively associated with disease remission. CONCLUSION: Impairment in TFR cells might contribute to aberrant IgE production in patients with AR, and AIT improves defective TFR cell function. TFR cells might serve as a potential biomarker to monitor clinical response to AIT.