Adoptively transferred BM-DCs colocalize and migrate within LVs. (A-C) Characterization of DCs generated from the BM of CD11c-YFP mice. (A) CD11c and YFP expression. (B-C) Overnight incubation in presence of LPS (0.1 μg/mL) induced further up-regulation of (B) I-A/I-E and of (C) CD86. (D-F) YFP⁺ DCs were injected into the ear skin and intravital imaging started after 4 to 6 hours. (D) Many DCs were found to colocalize with LVs, as indicated by white arrows. Scale bar: 100 μm. (E) Confocal analysis with z-axis projections confirming the intralymphatic location of a selected DC. Left: maximum intensity projection. Right: z-axis projection. Scale bar: 100 μm. (F) DCs actively migrate within LVs. Large picture on the left: confocal image stack showing green DCs within a red lymphatic vessel. Following pictures: sequential images showing elongated DCs that actively migrated within a lymphatic vessel. Numbers in the top-right corner indicate the minutes imaged. For simplicity reasons, only the green channel is shown. White lines outline the lymphatic vessel. White arrows indicate the direction of DC migration. Scale bars: 50 μm. (G) Quantification of the velocity of DC migration in the interstitium and within LVs. Each dot represents one tracked cell. Pooled data from 4 (interstitial) and 7 (intralymphatic) different experiments are shown (***P < .001). Gamma corrections were applied to panels D and E to enhance visibility of LVs.