Fig. 3.

TLN T cells use ballistic multicellular streaming to migrate. (A) Timelapse imaging of the TLN in adult tg(lck:GFP;cd4-1:mCherry) zebrafish shows the directional migration of 3 outlined T cells. (B and C) Average T cell velocity (B) and directionality (C) of T cells within the TLN, with each dot corresponding to the average of all T cells from an individual fish pooled from three independent experiments. (D) A plot shows the average displacement vs time of T cells migrating in the TLN. (E) Cell motility is characterized with a log–log plot of mean squared displacement (MSD) versus time where MSD ∝ t^α. The mean α for the 5 fish of 1.9022 indicates superdiffusive motion near the ballistic regime. (F) Imaging shows the head-to-tail interaction between two T cells. mm:ss, scale = 10 microns. (G) Timelapse imaging shows five outlined T cells in a tg(lck:GFP;cd4-1:mCherry) zebrafish forming, breaking, and reforming head-to-tail interactions as they migrate through the TLN of a 6-WPF juvenile fish, with the final frame showing the cell tracks. (H and I) Imaging of the TLN in tg(lck:GFP;mpeg1:mCherry) shows T cells organizing into a fibrous network with embedded macrophages as TLN goes from maturing (H) to fully mature (I) in late juvenile or adult zebrafish.