Fig. 1

CD28 dimer interface mimetic peptide p2TA inhibits signaling through CD28. A The complex between CD28 (blue) and B7-2 (pink). The extracellular domain of CD28 is oriented such that it enters the T cell at the top and that of B7-2 is oriented such that it enters the antigen-presenting cell at the bottom. In CD28, p2TA sequence within the dimer interface is shown in green and the B7 binding site (MYPPPY) in yellow. Because the structure of the CD28/B7-2 complex remains unresolved, CD28 (1YJD.pdb [7]) was superimposed on CTLA-4 in the CTLA-4/B7-2 complex (1I85.pdb [14]). B–G PBMC from a single human donor were induced with αCD3 (B–D) or αCD3/αCD28 monoclonal antibodies (mAb) (E–G) alone (○) or in the presence of 10 µg/ml of p2TA (▲) or pe12 (●). At times shown, IL-2, TNF-α and IFN-γ in culture medium were quantitated in triplicate. Data are mean and SEM. Representative data of 3 experiments are shown