Chemokine receptor and costimulatory molecule expression in CD27+ and CD27- switch memory B cells from synovial fluid of oligoarticular JIA patients Next, CD27+ and CD27- switch memory B cells were characterized with flow cytometry for the expression of CC chemokine receptors (R) (CCR1-CCR9) and CXCR (CXCR1-CXCR5), as well as for the CD80 and CD86 costimulatory molecules. Here, CCR9 is linked to juvenile idiopathic arthritis.