CXCR3, for which CXCL11 is a ligand, is likely to mediate the infiltration of T cells into the synovial tissue of rheumatoid arthritis patients, because this receptor is highly expressed in CD4+ T cells that accumulate in their synovial tissue [83], and accumulation of these T cells in the synovium is associated with expression of CXCR3 ligands by synovial fibroblasts [84,85]. Here, CD4 is linked to rheumatoid arthritis.