CD4+ KJ1-26+ cells from tolerant mice have the phenotype of memory regulatory cells. On day 0 BALB/c mice were injected with 2.5 × 106 CD4+ KJ1-26+ cells and, on the same day, treated with OVA and anti-CD4/anti-CD8 mAb. Mice were boosted six and ten weeks post-priming. Three days after the last boost mice were sacrificed and spleens were removed, labeled with CD4-specific mAb and KJ1-26 (panel a), and either, CD44-(panel b), CD45RB-(panel c), CD62L-(panel d), CD25-(panel e), GITR-(panel f), CTLA4-(panel g) and FOXP3-(panel h) specific mAb. Panel a is a representative dot plot of splenocytes labeled with CD4-specific mAb and KJ1-26. The top rectangle contains all CD4+ cells including the CD4+ KJ1-26+ cells (double positive). Samples shown in panels b–h are gated on total CD4+ cells (upper rectangle in panel a) and show the expression of each marker on CD4+ KJ1-26− (left of the vertical line) and CD4+ KJ1-26+ (right of the vertical line). The horizontal line marks the fluorescence intensity of the isotype control for each specific mAb.