CXCR1 and rheumatoid arthritis: The high frequency of RA peripheral blood and synovial membrane memory B cells expressing pro-inflammatory chemokine receptors, such as the IL8-receptors CXCR1 and CXCR2, or CCR2 (a negative modulator of cytoskeleton rearrangement and immature B cell migration [51]), stresses the potential role of interactions of memory B cells with other effector cells of the immune system that could contribute to the perpetuation of chronic synovitis.