The effect of CTLA4 on T cell motility may depend on the type of T cells and their settings. (A) The velocity of CD8⁺ OT1 T_eff cells (n = 3 mice, 40 cells, mean ± SEM) in ACE islet grafts in B6 mice is compared with that of CD4⁺ BDC2.5 T cells in ACE islet grafts in NOD.SCID mice. For CD4⁺ BDC2.5 T cell analyses, the CD4⁺ T_eff cells (n = 5 mice, 110 cells; mean ± SEM) and CD4⁺ BDC2.5 T_reg cells (n = 5 mice, 101 cells, mean ± SEM) were from animals injected either with T_eff and T_reg cell mixture (the second and third groups) or from CD4⁺ BDC2.5 T_eff cells only (fourth group, n = 3 mice and 107 cells). Each dot represents one cell and the lines in plots represent mean ± SEM. (B and C) Transient change of intra-graft CD4⁺ BDC2.5 T cell velocities after anti-CTLA4 treatment (n = 30–90 cells per group for each time point; mean ± SEM). (D and E) The effect of CTLA4 modulation on displacement (D) and velocity (E), respectively, on intra-graft CD8⁺ OT1 T_eff cells. Animals were treated with anti-CTLA4 antibodies (n = 3 mice) or PBS or hamster Ig control (n = 4 mice), or they carried a CTLA4 RNAi transgene (n = 3 mice). Data represent two experiments and are from analyses of 40 cells (mean ± SEM) in each group. Each dot in E represents one cell. **, P < 0.01; ***, P < 0.001. See Videos 5 and 6.