Figure 3

CD19⁺ and CD19^- plasma cells detectable in bone marrow cells from autoimmune patients and controls. Bone marrow (BM) cell suspensions were obtained from iliac crest or femoral head samples from autoimmune or nonautoimmune control individuals and stained for CD38 and CD19 (clone SJ25C1), and in some cases additionally for CD138, CD3 and CD14. Dead cells were excluded by adding DAPI and gating on DAPI^- cells. Plasma cells (PCs) were identified based on light scatter properties and high expression of CD38. CD38^high PCs showed co-expression of CD138 and lacked that of CD3 and CD14. (a), (b) Nonautoimmune individuals. (c), (d) Patients as indicated. (a) Red histogram depicts PCs stained for CD19, black histogram shows isotype control-stained PCs, blue histogram shows lymphoid cells including CD19⁺ B cells for comparison. Note that control-stained and CD19-negative PCs exhibit an increased fluorescent background signal as compared with other lymphoid cells. (b) to (d) Black histograms represent PCs; red histograms depicting lymphoid cells including CD19⁺ B cells are shown for comparison. Markers define CD19⁺ and CD19^- PCs, respectively. Frequencies represent proportions of CD19⁺ cells among PCs. AAV, ANCA-associated vasculitis; DAPI, 4',6-diamidino-2-phenylindole; SLE, systemic lupus erythematosus.