Persistence of vaccine-specific GC B cells after human influenza virus vaccination. Related to Fig. 1. (A) Flow cytometry gating strategy for PBs from blood. (B) Flow cytometry gating strategy for HA-binding GCs in lymph nodes (LN). (C) Flow cytometry gating of total GC B cells (CD20⁺ CD38^int) and HA-binding GC B cells (CD20⁺ CD38^int HA⁺) in the LN from participant 04. Cells were pregated on CD4⁻ CD19⁺ IgD^lo live singlets. Dagger indicates samples were excluded from further analysis due to low cell recovery or blood contamination.