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. 2019 Jan 22;129(2):850–862. doi: 10.1172/JCI123366

Figure 6. Stem antibody and memory B cells are expanded by seasonal influenza vaccination in humans.

Figure 6

(A) Serum endpoint total IgG titers of antibody binding the HA-FL (blue) or the stabilized HA stem (red) proteins at baseline and following immunization (day 28 [d28]) with seasonal IIV3 (n = 29) or IIV4 (2016: n = 18; 2017: n = 21). (B) Representative flow cytometric plots of IgG+ memory B cells from IIV4 (2016 season) recipients double stained with recombinant HA-FL or HA stem probes (CA09). Memory B cells were defined as CD19+IgD–IgG+ after prior exclusion of doublets, dead cells, and CD3+, CD14+, CD16+, CD8+, and CD10+ cells. Frequency (C) and percentage change (D) of IgG+ memory B cells binding HA-FL or HA stem between baseline and after IIV4 (2016 season) immunization (n = 18). (E) Representative flow cytometric plots of IgG+ memory B cells from IIV4 (2017 season) recipients costained with recombinant HA-FL (A/Michigan/45/2015) or HA stem probes (CA09). Frequency (F) and percentage change (G) of IgG+ memory B cells binding either HA-FL or HA stem between baseline and after IIV4 (2017 season) immunization (n = 21). Data represent the mean ± SEM. *P < 0.05, by Mann-Whitney U test (A, C, and E).