Studies have shown that the frequency of Th22 cells in the peripheral blood of ankylosing spondylitis (AS) patients is increased (20, 154), while other studies have shown that there is no difference in IL-22+CD4+ and IL-22+CD8+ T cells between AS patients and healthy controls; however, the secretion of IL-22 by circulating mucosal-associated invariant T (MAIT) cells is increased in AS patients (90). This evidence concerns the gene IL22 and ankylosing spondylitis.