Figure 3: Tregs engage immigrant DCs near the lymph node capsule.
From: Imaging regulatory T cell dynamics and CTLA4-mediated suppression of T cell priming
(a) LPS-activated CMTMR-labelled DCs (red) imaged in the draining inguinal lymph node 24 h after subcutaneous injection into a Foxp3EGFP mouse, showing immigrant DCs encountering and making contact with numerous endogenous Tregs (green) directly beneath the collagen capsule (blue) of the lymph node (major tick marks=20 μm, 50 μm z-stack). See Supplementary Video 6. (b) Close-up image of a DC (red) near the collagen capsule and its interactions with several Tregs (green). Major tick marks=10 μm. (c) Space-filled rendering of the DC (red) from b and an associated Treg (green) with track (grey, 39:27 (min:s) duration of imaging), showing close association between Treg and DC (scale bar, 5 μm). (d) Time sequence (times shown in min:s) showing interactions of Tregs (green with grey tracks) engaging recently immigrated DCs (red). (e) Experimental design to examine the effect of LPS-activated DCs on OTII Tconv cells and Tregs. LPS-activated DCs from an ECFP mouse were injected into a Foxp3EGFP mouse followed by adoptive transfer of CMTMR-labelled OTII Tconv cells at 24 h and 2P imaging in the draining lymph node 12 h later. (f) Snapshot showing adoptively transferred OTII Tconv cells (red), LPS-activated DC (blue) and Tregs (green). Scale bar, 30 μm. See Supplementary Video 7. (g) Contact durations of Tregs with LPS-DCs (n=110 contacts) and Tconvs with LPS-DCs (88 contacts). Data pooled from three experiments each. (h) Effect of LPS-activated DCs on Treg velocities. Control velocities in the absence of LPS-DCs: Treg n=296; OTII Tconv cells n=213. In the presence of LPS-DCs, OTII Tconv-cell velocity did not change appreciably (P=0.7, n=207, Mann–Whitney U-test), whereas Treg velocity was reduced (n=193). Data pooled from three experiments each. NS, not significant.
