Figure 5: Tregs engage antigen-specific clusters of DCs and Tconv cells in a CTLA4-dependent manner.
From: Imaging regulatory T cell dynamics and CTLA4-mediated suppression of T cell priming
(a) Experimental design to image the role of CTLA4-B7 in Treg interactions. Ova-pulsed DCs from ECFP mice were adoptively transferred into Foxp3EGFP mice 24 h prior to CMTMR-labelled OTII Tconv cells; imaging was performed 12 h after OTII Tconv-cell transfer. Animals received 150 μg of either ITC or αCTLA4, 30 min after adoptive transfer and 4 h prior to imaging. (b) Still image showing DCs (blue), OTII Tconv cells (red) and Tregs (green) in a node from αCTLA4-treated mouse. Scale bar, 50 μm, see Supplementary Video 9. (c) Superimposed tracks of OTII T cells (red) and Tregs (green), with their origins normalized to the centre of a DC. Cells were tracked for 10:14 (min:s). n=21 for ITC and 34 for αCTLA4. (d) Treg contact history map. Each horizontal bar represents a single Treg, with contacts colour coded as in Fig. 4d. Note the shorter red and blue bars as compared with Fig. 4d, indicating that Tregs spend less time interacting with Tconv cells and DCs in the presence of αCTLA4. (e) The percentage of OTII T cells in stable contact with a DC was increased by αCTLA4 treatment, compared with control (n=21 and 14, respectively). Imaging period minimum: 20 min. (f) Tconv and Treg contact durations with antigen-bearing DCs. OTII Tconv:DC contact durations are increased in the presence of αCTLA4 (n=78) relative to ITC control (n=80). Treg:DC contact durations were shortened in the presence of αCTLA4 (n=42) relative to ITC (n=83).
