2d). When we performed correlation analysis to find the relationship between this population and disease activity, it did not reach statistical significance because the number of patients with active SLE was not great enough (data not shown). However, linear regression analysis showed that the proportion of CS1-positive B cells increases linearly with increased SLEDAI score (P = 0·035, R2 = 11·4%; Fig. 2e). Because the proportion of cells can be affected by a relative lymphopenia in patients Selleck X-396 with SLE, we also determined the mean fluorescence intensity ratio (MFIR),

which represents the density of receptors at the single-cell level (Table 2). MFIR of CS1+ cells in total PBMCs was not significantly different between healthy controls and SLE patients. However, CD3+ CS1+ T cells up-regulated CS1 expression significantly at the single-cell level. In contrast, all NK cells down-regulated CS1 expression significantly compared to healthy controls. For analysis of B cells, we gated total B cells including both CS1-positive and CS1-negative

B cells, because percentages of CS1-positive B cells are very low in healthy controls. Despite the significant percentage increase of CS1-positive B cells, MFIR Selleck Nivolumab shift in CS1+ cells gated within total B cells did not reach significant levels compared to healthy controls. Collectively, these data suggest that CS1-expression is regulated dynamically at the cellular and molecular levels in SLE. Recently, a number of different subsets of circulating B cells were reported in SLE, including naive B cells, memory B cells, plasma cells and plasmablasts. These cells can be identified by surface markers such as surface immunoglobulins (IgM and IgD), CD19, CD20, CD21, CD27, CD38, CD95 and human leucocyte antigen D-related (HLA-DR). Interestingly, we found that CS1 expression can also identify different subsets of SLE B cells.

Figure 3 shows that co-staining with CD19 and CS1 distinguishes three distinct subsets of B cells: CD19-middle, CS1-negative B cells; CD19-high, CS1-low B cells; and CD19-low, CS1-high B cells (best illustrated by Fig. 3d). As shown in Fig. 3a–c, healthy individuals had CD19-middle, CS1-negative B cells as a major B cell population. In contrast, most SLE patients had all three B cell populations, and all patients exhibiting a high proportion of Cediranib (AZD2171) CS1-positive B cells essentially had CD19-high and CD19-low B cell populations. As shown in Fig. 3e,f, some SLE patients displayed CD19-low, CS1-high B cells as their major B cell populations. Notably, as seen in Fig. 3f, one patient with active SLE (patient 1, SLEDAI = 15) displaying the highest percentage of CD19-low, CS1-high B cells had a very low number of CD19+ B cells, probably affected by lymphopenia. Next, we analysed the proportion of 2B4-expressing cells in total PBMCs, CD3+ T cells, CD56+ NK cells and CD14+ monocytes in patients with SLE and healthy controls. As shown in Fig.