WASp is required for in vitro DC/T-cell interaction. (A) Analysis of expression of DC maturation markers, representative histograms are shown of 3 experiments. (B) Endocytosis and processing of self-sequenced, fluorescently labeled ovalbumin (DQ-OVA) over time, C57BL/6 and WAS KO n = 2. (C) Proliferation of OT-II T cells, induced by coculture with BMDCs at indicated ratio, was determined by CFSE dilution. Shown are representative histograms of 12 experiments. (D-E) DC-T-cell interactions, shown are stills from a 60-minute recording (1 frame/min) of DCs (red) interacting with OT-II T cells (green), arrows indicate when cells are in contact and last frame shows individual tracks of T cells. (F) Quantification of the average contact time and (G) frequency of T cells contacting the same DCs from the imaging shown in panels A and B, data are shown as averages ± SEM, 1 representative experiment of 4 is shown with > 40 cells analyzed per condition, P values are indicated (1-way ANOVA).