K118I/K120P CD28 binds CD80 with high avidity in the absence of TCR signaling.

Cell frequency adhesion of CD28-deficient, DO11.10 T cells retrovirally transduced with WT CD28-YFP or K118I/K120P CD28-YFP to control beads (None) or beads coated with CD80 in the absence (Unstim) and after (Anti-CD3) stimulation. Cell adhesion data are presented as mean ± SD of the adhesion frequency for individual cells (25 impingements each; n = 6–7 for control beads and 12–14 for CD80-Fc beads; p values for t tests between samples are shown).