Fig. 2.

Increased proportion of CS1-expressing B cells in systemic lupus erythematosus (SLE) patients is observed with increased disease severity. (a–d) Comparison of the proportion of CS1-expressing cells in gated populations from peripheral blood mononuclear cells (PBMCs) between SLE patients (SLE) (n = 40) and healthy controls (HC) (n = 30). (a) Total lymphocyte population was gated based on forward- and side-scatter. (b) T cells stained with anti-CD3-fluorescein isothiocyanate (FITC) were gated. (c) Natural killer (NK) cells stained with anti-CD56-allophycocyanin (APC) were gated. (d) B cells stained with anti-CD19-APC were gated. For each gate, the proportion of CS1-expressing cells was calculated by subtracting the percentage of phycoerythrin (PE)-conjugated mouse immunoglobulin (Ig)G2a-stained cells from the percentage of PE-conjugated anti-CS1 antibody-stained cells. Asterisk indicates significant differences between HC and SLE groups. (e) Linear regression analysis shows that there is a linear relationship with positive slope between the proportion of CS1-positive B cells and SLEDAI scores (P= 0·035).