Th17 cell escape from myeloid cells and cell death within myeloid cells after internalization. Co-cultures of hippocampal slices from CX3CR1^GFP pups with pathogenic B6.2D2.CFP.Th17 cells were stained with Image-iT LIVE Red Caspase-3 and -7 Detection Kit to identify apoptotic cells. (A) Representative identification of viable T cells (blue), early apoptotic T cells (blue and red), and apoptotic/dead cells (red) engulfed by myeloid cells (green) in these co-cultures (n = 5 co-cultures from four different experiments). Scale bars = 10 µm. (B) Representative sequence of an engulfed Caspase-3/7–negative B6.2D2.CFP Th17 cell (viable, false colored in red for better visualization) imaged over a time period of 120 min via two-photon microscopy ex vivo (n = 4 co-cultures from three different experiments). Scale bars = 15 µm. Arrows point to a stably engulfed T cell. (C) Representative sequence of an escaped viable T cell (false colored in red for better visualization) for 44 min ex vivo (n = 4 co-cultures from three different experiments). Scale bar = 15 µm. Arrows point to an escaping T cell. (D) Mean (± SEM) T cell motility parameters of viable T cells before (n = 6 cells from two different experiments) and after (n = 6 cells from two different experiments) the interaction with myeloid cells during the escape process ex vivo. Statistical analysis was performed using two-sided Student’s t tests. ns, not significant. (E) Mean (± SEM) percentage of engulfment and escape among the engulfment processes (EPs) ex vivo. n = 33 organotypic slices from 20 different experiments. Statistical analysis was performed using two-sided Student’s t tests. *, P < 0.05.