Figure 6. Reduced FcγRIIB expression in MZ B cells from patients with SLE.

High-dimensional spectral flow cytometry was used to identify multiple B cell subsets within PBMCs from patients with SLE (n = 15) and healthy donors (HD) (n = 10). (A) Expression of CD32B/C in CD27^– and CD27⁺ B cells. (B) Live B cells were clustered using FlowSOM and are shown in a UMAP plot. Live B cells from healthy donors and patients with SLE were concatenated from each donor (n = 250,000 cells per group). (C) Expression of CD32B/C among all B cell clusters in the UMAP plot. (D) Representative example of CD32B/C expression in MZ-like B cells from healthy donors and patients with SLE, including the FMO control. (E) Summary of CD32B/C expression in MZ B cells. (F) Summary of CD32B/C expression in cells in all FlowSOM clusters. (G) Expression of CD32B/C in MZP cells identified by manual gating as live CD19⁺CD27^–IgD⁺CD38^loCD21⁺CD24^hi. (H) Representative examples of CD80 expression and gating in MZ B cells from healthy donors and patients with SLE. MZ B cells from healthy donors and patients with SLE were concatenated from each donor (n = 25,000 cells per group). (I) Summary of the percentage of CD80⁺ MZ B cells from healthy donors and patients with SLE. (J) Correlation of the percentage of CD80⁺ cells and CD32B/C MFI in MZ B cells. Data are shown as the median, with each symbol representing an individual donor (n = 10 for healthy donors; n = 15 for patients with SLE). **P < 0.01 (A) and other P values were determined by Mann-Whitney U test (E–G and I) or Spearman’s rank test (J). Act. Nv, activated naive; Rest. Nv, resting naive; Atyp. UnswM, atypical unswitched memory; Act. SwM, activated switched memory; Rest. SwM, resting switched memory; PB, plasmablast.