Figure 4
Altered CXCR7 expression on SLE B cells. (A) Surface expression of CXCR7 on CD19+-gated PBMC from healthy and SLE subjects was determined by flow cytometry using the unconjugated 9C4 (empty histograms) or isotype control (filled histograms) mAb followed by a PE-conjugated goat anti-mouse F(ab’)2 Ab. CXCR7-transduced (versus parental) HEK 293 T (HEK) cells were used as a positive control for staining. Displayed data are representative plots of the MFI of CXCR7 at the surface of total B cells from a healthy individual and two patients with either inactive or active SLE (left panel) or of HEK cells transduced with CXCR7 or left untransduced (right panel). (B) The percentage of total (CD19+) B cells, naive (CD19+CD27-) B cells, memory (CD19+CD27+) B cells and PC (CD19lowCD27high) expressing CXCR7 in healthy and SLE subjects are shown. Box plots show the median values, 25th and 75th quartile and the range of values. Kruskal-Wallis H test and associated P values are indicated. *P < .05, **P < .005 and ***P < .0005 compared with control B cells (as determined using the Mann–Whitney U-test). (C) CXCR7-positive fraction values obtained within total B cells for each SLE patient were plotted as a function of SLEDAI scores. Correlation factor (r, Spearman’s) and P value are indicated.