Fig. 4

CD28 dimer interface mimetic peptides p4TA and p5TA attenuate B7/CD28 engagement, signaling through CD28, and inflammatory cytokine production. A, B Human PBMC were induced with αCD3/αCD28 monoclonal antibodies alone (open symbols) or in the presence of p4TA (A) or p5TA (B) at concentrations shown (µg/ml) (filled symbols). At times shown, IL-2 and TNF-α in culture medium were quantitated. Data in A and B are for PBMC from distinct human donors. Representative data of 3 experiments are shown. C, D p4TA attenuates intercellular B7/CD28 engagement. Receptor engagement was assayed by flow cytometry as in Fig. 3D for B7-2/CD28 engagement and as in Fig. 3K for B7-1/CD28 engagement. Data are mean and SEM of three independent experiments (contour plots: Additional file 1: Fig. S5A and S5B). E, F p5TA attenuates intercellular B7/CD28 engagement. Receptor engagement was assayed by flow cytometry as in C and D. Data are mean and SEM of three independent experiments (contour plots: Additional file 1: Fig. S5C, D). Intercellular receptor engagement was compared using the one-tailed unpaired student’s t-test; *p < 0.05, **p < 0.005, ***p < 0.001