Dynamics of pDC–T-cell interactions. pDCs and cDCs were isolated from Flt3-L-driven cultures. Immature (i) or mature (m) DCs were incubated with OVA peptide and seeded onto fibronectin-coated coverslips. OT-II CD4⁺ T cells labeled with the green probe calcein were added to the chambers. Contacts between T cells and DCs were monitored by time-lapse videomicroscopy for 30 minutes, and the contact times of individual DC–T-cell pairs were measured. (A) Representative images are shown of different time frames of the video-recorded movies. Each T cell that interacted for more than 15 minutes is marked by a different colored dot. (B) T-cell–DC interactions were classified into 3 categories based on the duration of the interaction: short (< 5 minutes), medium (5-15 minutes), and long (> 15 minutes). Data represent the proportion of each category.