Figure 3: Frequency of proliferating B-cells expressing CD27 after in vitro vaccine stimulation. PBMC were labelled with CFSE and cultured with influenza vaccine for five days. (a) Gating strategy to identify CD19+ proliferating cells (CD19+CFSElow). (b) Pre (T0) and Post (T1) vaccination frequencies of CD27+ cells among CD19+CFSElow cells; n=8 healthy controls, n=6 COPD subjects. (c) Examples of CD19 and CD27 expression on CD19+CFSElow cells from PBMC collected post vaccination (T1) from 5 healthy controls (upper panel) and 5 COPD patients (lower panel). Percentages of CD19+CFSElow expressing CD27 are indicated in boxes. (d) The frequency of post vaccination (T1) CD27+ cells among CD19+CFSElow cells; n=19 COPD subjects and 12 healthy controls. Results are shown as median IQ.