CX3CR1 and rheumatoid arthritis: The chemokine receptor profile of ABCs included high expression of inflammatory‐associated and RA synovium‐localization chemokine receptor genes, such as CXCR3 and CX3CR1 (fractalkine receptor), and low expression of chemokine receptor genes whose products mediate migration of leucocytes into and within lymphoid organs, such as CXCR4 and CXCR5 (Figure 1f).