Compared to healthy subjects, increased circulating (serum and plasma) levels of IL-37 have been documented in various inflammatory and autoimmune conditions, including rheumatoid arthritis (18–24), ankylosing spondylitis (25), endometriosis (26–28), systemic lupus erythematosus (29–31), Guillain-Barré syndrome (32), Graves’ disease (33), and multiple sclerosis (34, 35), as well as in spinal cord injury (36) where its levels are frequently correlated with measures of disease activity. Here, IL37 is linked to ankylosing spondylitis.