Figure 8.

Selective CD28 blockade controls Tfh recall responses to KLH immunization in mice more effectively than CTLA-4-Ig. (A) Mice were immunized with KLH and LPS and treated with either CTLA-4-Ig or the Fab-PV1-Peg antibody, an anti-CD28 antagonist effective in mice, either on day 0 to study primary responses or 1 month after a first immunization to study memory responses. (B) Postimmunization draining popliteal LNs were collected, and levels of Tfh cells (CXCR5⁺PD1⁺) among the CD4⁺ or CD4⁺CD44⁺ population were assessed by flow cytometry as represented in the flow cytometry contour plot. (C) Time course under control condition (n=3). Percentage of Tfh cells among CD4⁺CD44⁺ (D) on day 6 postimmunization or (E) 3 days after reimmunization according to conditions indicated on the x axis (n=5 per group). Data are means±SEMs. One-way ANOVA and Kruskal–Wallis tests were used. *P<0.05; **P<0.01.