Figure 2. Metabolic phenotypes of B cells. (A) Graphs show mean fluorescent intensity (MFI) of stains for the indicated markers in or on different B cell subsets, i.e., naïve B cells (IgD+CD19+CD27-CD38-), unswitched memory B cells (IgD+CD19+CD27+CD38-), switched memory B cells (IgD-CD20+CD19+CD38+CD27-) and ASCs (IgD-CD20-CD19+CD38+CD27+) of younger (open circles) or aged (grey squares) individuals. Graphs show results for individual samples with means. Statistical difference indicated with lines and stars above as in legend to Figure 1 were calculated with multiple type 1 error corrected t-tests. (B) Samples were separated into those with high antibody responses (~1/3 of samples) and low antibody responses (~1/3 of samples). To this end samples were sorted according to magnitude of increases of the different antibody responses (VNAs, IgA, IgM and IgG titer increases) after vaccination as compared to baseline. The top and bottom samples (~1/3 of all samples each) were selected and analyzed. Significant differences were seen for the MFI for the SIRT1 stain in ASCs in high versus low IgG responders to H1N1 and H3N2. Lines with stars above indicate significant differences as described in legend to Figure 1. Abbreviations: CPT-1: carnitine palmitoyltransferase 1; FOXO1: Forkhead box (FOX) protein O1; MROS: mitochondrial reactive oxygen species; SIRT1: Sirtuin 1.