Phenotypic profile of G6⁺ B cells from healthy donor D1. Peripheral blood mononuclear cells were analyzed by 4-color fluorescence-activated cell sorting. (A) Distribution of G6 reactivity between CD27⁻ and CD27⁺ B lymphocytes (CD19 selected). The histogram plots compare the surface expression of CD5 (B), CD23 (C), CD38 (D), IgM (E), and IgD (F) in G6⁺ and G6⁻ cells, gated as in panel A (thin line, G6⁻ CD27⁺; thick line, G6⁻ CD27⁻; shaded, G6⁺; dashed line, isotype controls). Histograms are normalized to the maximum for each peak.