In fact, the pathological role of XCL1-XCR1 axis has been implicated in numerous chronic inflammatory diseases, including rheumatoid arthritis, inflammatory arthritis, Crohn's disease, acute allograft rejection, autoimmune disorders, encephalomyelitis, crescentic glomerulonephritis, and inflammatory bowel disease (18–23). This evidence concerns the gene XCL1 and rheumatoid arthritis.