Activated T cells interact with airway-adjacent DCs. (A) Interactions of T cells (red) and DCs (green) illustrated by a time course showing T cells swarming over the surface of multiple DCs but always remaining in contact with at least one. (B) OTII T cell accumulation within 75 µm of a representative airway compared with DC accumulation within the same area in an OVA-challenged mouse. (C) Percent duration of a 30-min video that OTII T cells were in contact with at least one DC in either the airway or alveolar region. (D) Track speed means for previously activated antigen-specific (OTII) or nonspecific (SMARTA) airway T cells. (C and D) Error bars represent SEM. (E) Activated antigen-specific (OTII) T cells were stained with CMTMR and Fluo-4 and transferred into OVA-challenged CD11c-EYFP mice 6 h before imaging. Percentage of maximum mean fluorescence intensity (MFI) of Fluo-4 in previously activated T cells. Gray background indicates the time that T cells are in contact with a DC. Each panel represents one cell. (F) Transferred T cell stained with CMTMR and Fluo-4 (gated on the CMTMR signal of the cell, pseudocolored) moves toward an airway, transiently interacting with a DC (teal) on the way. Bars: (A, left) 50 µm; (A, right) 15 µm; (F) 10 µm. Time stamps are shown in minutes/seconds. Images and quantification are representative of at least three mice per group from at least two independent experiments.