DC mobility increases after contact with T cells and superantigen. Dendritic cells (DCs; 105) were exposed to superantigen (Sag) and seeded on polylysin-coated coverslips. T cells were added (3 × 105) before image recording. Images were recorded every 3 minutes for 5 hours. (A) Still images taken from Videos S1,S2,S3 (DC + T cells, DC + Sag, and DC + T + Sag, respectively). Arrows point to individual DCs. Bar, 20 μm. Right panels, mobility tracks of all DCs present in the fields from Videos S1,S2,S3 are shown. Results are representative of 3 experiments. (B,C) DCs are recruited to the sites of DC–CD4+T cell interaction. DCs stained with DiD (red) pulsed with TSST1 (+ Sag) or left unpulsed (-Sag), were seeded on coverslips together with unpulsed immature CFSE-labeled DCs (green) and CD4+ T cells and cultured for 6 hours. Cells were then fixed and coverslips mounted for confocal microscopy. (B) Representative images are shown. Bar, 40 μm (C) Percentages of DiD-DC in contact with CFSE-DC. Results represent means plus or minus SD of 3 independent experiments (30-40 conjugates analyzed per experiment). Significance assessed by Student unpaired t test (**P < .005).
