Figure 6: CTLA4 is critical for Tconv–Treg interactions during priming.
From: Imaging regulatory T cell dynamics and CTLA4-mediated suppression of T cell priming
(a) CFSE dilution in OTII Tconv cells 72 h following transfer into WT mice primed with Ova-LPS pulsed DCs. Green and red lines for draining lymph node (DLN) of ITC- and αCTLA4-treated mice, respectively; grey line for contralateral LN with αCTLA4. (b) In vivo proliferation of OTII Tconv determined by CFSE dilution; data from four to five mice with αCTLA4 or ITC control treatment. (c) In vitro proliferation of Tconv (WT, left, and B7-KO, right) after stimulation with anti-CD3/28 Dynabeads with (blue) and without (red) WT Treg co-culture (1:1). (d) Inhibition of WT and B7-KO Tconv-cell proliferation by WT Tregs; red bars indicate mean values, data pooled from two independent experiments. (e) Left: Ova-pulsed DCs (blue) interacting with OTII Tconvs (red) and Tregs (green) in a Foxp3EGFP mouse. Right: tracks of Tconvs and Tregs that touched a DC at least once during imaging (20:55 (min:s)); tracks normalized to DC position; scale bar, 10 μm. (f) Left: Ova-pulsed DCs (blue), OTII Tconvs (red) and Tregs (green) in Foxp3EGFP mouse treated with αCTLA4. Right: tracks of Tconvs and Tregs that interacted with a DC (blue) at least once during imaging (20:33 (min:s)). Scale bar, 10 μm. (g) Contact durations of OTII Tconvs in the absence and presence of LPS-DCs. Basal: Tconv:Tconv, n=135; Tconv:Treg, n=234. LPS-DCs present: Tconv:Tconv, n=108; Tconv:Treg, n=145. (h) Contact durations of OTII Tconvs in the presence of Ova-pulsed DCs after treatment with 150 μg isotype control (ITC) or αCTLA4 antibodies. ITC treated: Tconv:Tconv, n=101; Tconv:Treg, n=108. αCTLA4 treated: Tconv:Tconv, n=87; Tconv:Treg, n=152. (i) Velocities of OTII Tconvs and Tregs under basal conditions after treatment with ITC or αCTLA4 antibodies. Tconv tracks: n=268 (ITC) and 238 (αCTLA4); Treg tracks: n=296 (ITC) and 213 (αCTLA4). (j) Velocities of OTII Tconvs and Tregs in Ova-LPS-DC immunized mice after treatment with ITC or αCTLA4 antibodies. Tconv tracks: n=99 (ITC) and 114 (αCTLA4). Treg tracks: n=811 (ITC) and 305 (αCTLA4). NS, not significant.
