CXCR5 and systemic lupus erythematosus: Using PD-1 and CCR7 markers, CD4+CXCR5+ can be subdivided into two subtypes with similar phenotypes and functional properties in SLE PBMCs: (CD4+CXCR5+PD1highCCR7low) T cell and (CD4+ CXCR5+PD1lowCCR7high) T cell.