Fig. 1.

Gating strategies for the characterization of B cell subsets. The lymphocyte population was identified based on side-scatter (SSC) characteristics and CD45 expression (R1). B cells were defined further as CD19-expressing cells in the lymphocyte population (R2). CD19⁺ B cells were analysed either for the expression of IgD and CD27, CD24 and CD38 or CD21 and CD38. The following B cell populations have been delineated: CD27^-IgD⁺ (R3, naive B cells), CD27⁺IgD⁺ (R4, non-switched memory B cells), CD27⁺IgD^- (R5, switched memory B cells), CD27^-IgD^- (R6, CD27 negative memory B cells), CD24⁺⁺CD38⁺⁺ (R7, transitional B cells), CD24^-CD38⁺⁺ (R8, plasmablasts) and CD21^low CD38^low B cells (R9).