The alteration of CD4+ regulatory T cells in patients with ankylosing spondylitis
Objective To evaluate the alteration of CD4+ regulatory T cells in peripheral blood from patients with ankylosing spondylitis(AS). Methods Seventy-eight AS patients and 50 healthy individuals were included in this study. The proportion of CD4+CD25+CD127lo/- T cell population in CD4+ T cells as well as that cytotoxic T lymphocytes(CTL) and NK cells in lymphocytes was evaluated by flow cytometry. Serum TGF-β and TNF-α were measured by ELISA. The inhibitory function of CD4+CD25+ regulatory T cells was measured by mixed lymphocyte culture. Results The population of CD4+CD25+CD127lo/- T cells in peripheral blood of AS patients accounted for (4.36±1.21)% of CD4+ T lymphocytes, which was significantly lower than that in healthy individuals (P<0.05). The CD4+CD25+CD127lo/- T cells population in AS patients was positively correlated with TGF-β level, but negatively with TNF-α. Compared with healthy individuals, the function of CD4+CD25+ regulatory T cells in the inhibition of alloreactive T cells was lower in AS patients, which was related to the decreased secretion of TGF-β. Conclusion The CD4+ regulatory T cells in peripheral blood of AS patients are significantly decreased and its function is defective, which leads to immune regulatory dysfunction in vivo. It may be one of immune pathogenesis mechanisms of AS. 
 
Key words: 
Ankylosing spondylitis;  CD4+CD25+CD127lo/- regulatory T cells;  CD4+CD25+ regulatory T cells;  Mixed lymphocyte culture;  Transforming growth factor-β