Figure 5

CXCR3⁺ cTfh cells show a superior ability to support HCV-specific B cell expansion compared with CXCR3⁻ cTfh cells from individuals with HCV infection in vitro. (A) Representative flow cytometry plots and the percentage of plasma cells (CD38⁺ CD138⁺-gated CD3⁻ T cells) after CXCR3⁺ cTfh or CXCR3⁻ cTfh cells were cocultured with autologous memory B cells for 7 days in the presence of SEB (1 µg/ml). After 7 days, B cells were defined as CD3⁻ CD4⁻ cells because plasmablasts/plasma cells can downregulate CD19 and are CD20 negative. (B) Comparison of IgA, IgM and IgG production in the supernatant after CXCR3⁺ cTfh cells or CXCR3⁻ cTfh cells were cocultured with autologous memory B cells (n = 7). (C) Representative flow cytometry plots of HCV E2-specific B cells and comparison of HCV E2-specific B cells after CXCR3⁺ cTfh cells or CXCR3⁻ cTfh cells were cocultured with autologous memory B cells (n = 6). The paired t-test was used for the analysis.