TSLP promotes DC migration in the confined environment of microchannels. (A) After 20 hours of culture in medium or TSLP, DCs were added in the starting chamber of the microchannel system. They were allowed to spontaneously enter the fibronectin-coated 4-μm-wide channels, and phase-contrast images were recorded. The number of cells entering the channels dramatically increased after TSLP activation of DCs (arrow indicates an individual cell inside a microchannel). (B) Representative kymograph of an untreated DC and a TSLP-DC generated by sequential pictures of a DC within a microchannel. We can see the untreated DC changing direction several times during the recording. Raw phase-contrast images were processed to analyze cell movement as described in “Kymograph extraction and instantaneous velocity.” (C) After 20 hours of culture, DCs were allowed to spontaneously enter the fibronectin-coated 4-μm-wide channels, and phase-contrast images were recorded. Changes of direction through the channels were quantified for individual cells. TSLP-DCs exhibited a more straight movement. Only 10% of TSLP-DCs show changes in direction inside the microchannels. (D) Kymographs obtained in panel C were processed and analyzed to extract instantaneous speed of individual cells. The distributions of median and maximal speed of DCs precultured in control medium (left panels) or with TSLP (right panels) are not significantly different (P > .05). Data are from one representative of 3 independent experiments.