Fig. 2.

Human T cells use CTLA-4 to remove CD86 from dendritic cells. (A) Typical CD86 expression on a human monocyte-derived dendritic cell (DC) cultured in the absence of T cells. (B) DC cultured for 72h with anti-CD3-activated CD4⁺CD25⁻T cells (outlined in white) stained with anti-CD86 (green) and anti-CTLA-4 (red). Single staining is shown as white for equal contrast. Cells were co-cultured in the absence or presence of blocking anti-CTLA-4. (C) Quantitation of surface CD80 and CD86 expression on DCs after co-culture with T cells in the presence or absence of anti-CTLA-4 determined by flow cytometry. Data show MFI change pooled from >5 experiments with SEM. (D) Confocal micrographs of allogeneic DCs co-cultured overnight with CTLA-4-transfected (CTLA-4 TF) or control resting CD4⁺CD25⁻human T cells. Cultures were fixed and stained with anti-CD86 (green) or anti-HLA-DR (red). White arrowsheads highlight position of T cells, green arrowsheads highlight DCs. White images show single color staining for contrast. (E) Mean fluorescence intensity of surface CD86 on DCs after incubation with either CTLA-4-transfected or control T cells as determined by flow cytometry. All data are representative of at least 3 independent experiments. Error bars represent the SEM. Scale bars = 10 μM.