Fig. 1

CD27^–CD10^– tonsillar B cells express CD22 and internalize Emab. a, b Characterization of tonsillar B-cell subsets. Tonsillar cells were stained with fluorochrome-labeled mAbs against CD10, CD19, CD22, CD27, CD38, and IgD and analyzed using multicolor flow cytometry. a Representative flow analysis of gated live CD19⁺ cells showing B-cell subgating into CD10^–CD27^–, CD10^–CD27⁺, and CD10⁺CD27^+/– subsets; right histograms show expression of CD38 and IgD within each population. b Surface expression of CD22 quantified by flow cytometry and compared to corresponding B-cell subsets from PBMCs of healthy donors. Each dot on the graph represents individual donors. c Tonsillar B cells were stained with mAb specific for CD10, CD27, and CD20 (green) and with Emab, conjugated to Pacific Blue (purple). Cells were incubated at 4 or 37 °C, and Emab surface binding and internalization of CD10^–CD27^– cells was visualized by imaging flow cytometry. Data shown are representative of three independent experiments. Emab epratuzumab, PBMC peripheral blood mononuclear cell