Objective: Previous reports have shown an increase in peripheral blood mononuclear cells' (PBMC) Th17 cell subpopulation and tumor necrosis factor-α (TNF-α) secretion after in vitro stimulation with anti-CD3/CD28 or phorbol myristate acetate/ionomycin in ankylosing spondylitis (AS). The aim of our study was to determine whether there is a Th17 polarization not subjected to in vitro stimulation in patients with AS.
Methods: Nonstimulated PBMC were analyzed from 46 patients with AS, including 7 (15.2%) receiving tumor necrosis factor-α (TNF-α) inhibitors, 20 patients with rheumatoid arthritis, and 25 healthy controls. The surface phenotype of freshly isolated PBMC was determined by flow cytometry. Th1, Th2, Th17, and Treg subsets were defined as CD3+CD4+IFN-γ+, CD3+CD4+IL-4+, CD3+CD4+IL-17A+, and CD3+CD4+FoxP3+, respectively. Serum cytokines and interleukin 8 (IL-8) levels were quantified by Luminex technology.
Results: The percentages of Th17 and Th1 cells in AS were higher than in healthy controls (7.4% ± 1.8% vs 0.7% ± 0.2% and 4.0% ± 1.3% vs 1.1% ± 0.3%, respectively; p < 0.0001). Th17 and Th1 cell subsets in patients taking TNF-α inhibitors were lower than in those naive to such therapeutics and similar to healthy controls. Serum levels of IL-6, IL-17A, TNF-α, and IL-8 were significantly higher in patients with AS compared to controls.
Conclusion: The percentages of Th17 and Th1 cells in PBMC without in vitro stimulation, as well as cytokine and IL-8 levels, were significantly increased in patients with AS compared with healthy controls. These T cell subsets and cytokine profiles of patients with AS taking TNF-α inhibitors were similar to those of healthy controls.