CXCR5 and ankylosing spondylitis: Many studies have shown that an increased number of circulating CXCR5+CD4+ Tfh cells is associated with several of inflammatory diseases, such as CHB [25] and autoimmune diseases (systemic lupus erythematosus [34,35], ankylosing spondylitis [36,37], rheumatoid arthritis [38,39], polyangiitis [40], myasthenia gravis [41], and Sjögren’s syndrome [42]).