Fig. 3.

TCR stimulation promotes CTLA-4 trafficking and trans-endocytosis of CD86. (A) Acquisition of CD86-GFP from CHO cells by human CD4⁺ T cell blasts in the presence or absence of anti-CD3 stimulation. Right hand panels show the effect of anti-CTLA-4 antibody on GFP uptake. (B) SEB-specific CD4⁺ T cell blasts were incubated with either unpulsed or SEB-pulsed DCs. Cells were fixed and stained with anti-CD86 (green) and anti-CTLA-4 (red). Yellow indicates colocalization. Single colors are shown in white for equal contrast. (C) Surface levels of CD86 on DCs incubated with SEB-specific T cell blasts for 16h as determined by flow cytometry. (D) CD4⁺CD25⁺ (Treg) or CD4⁺CD25⁻T cells were incubated with DCs and anti-CD3 overnight, fixed, stained using anti-CD86 (green), anti-CD3 for T cells (blue), and visualized by confocal microscopy. Yellow arrow indicates CD86 puncta within T cells. (E) Surface levels of CD86 on DCs incubated with CD4⁺CD25⁺ (Treg) and CD4⁺CD25⁻T cells overnight determined by flow cytometry. All data are representative of at least 3 independent experiments. Error bars represent the SEM. Scale bars = 10 μM.