Figure 1

Figure 1: Flow cytometric analysis of B cell sub-populations After gating on lymphocytes according to forward (FSC) and side (SSC) scatter B cells were selected by CD19 surface staining. B cells were then analysed for CD27 and IgD expression to assess the percentage of IgD⁺ CD27^- B cells (1), IgD⁺ CD27⁺ B cells (2) and IgD^-CD27⁺ B cells (3). In addition, CD27⁺ and CD27^- B cells were selected and further assessed for surface IgD and IgM staining to determine the percentages of IgD⁺IgM⁺CD27⁺ unswitched memory B cells (4), IgD^-IgM^-CD27⁺ class switched memory B cells (5) and IgD⁺IgM⁺CD27^- naive B cells (6). B cells were further analysed for CD21 and CD38 surface expression to identify CD38loCD21lo B cells (7). In addition, B cells were analysed for IgM and CD38 surface expression to identify CD38⁺⁺⁺IgMhi transitional B cells (8) and CD38⁺⁺⁺IgM^-plasmablasts (9).