Impaired interaction with T cells resulting from mDia1 deficiency in DCs. (A) Time-lapse images of DC-T cell interaction ex vivo. OVA-pulsed CFSE-labeled B6 or mDia1^−/− BMDCs were injected into mouse footpads, and CMTPX-labeled OT-II CD4⁺ T cells were intravenously administered. The popliteal LNs were collected and the DC–T-cell interaction was monitored using 2-photon microscopy; typical images at 0, 14, and 25 minutes are shown. White and red dots represent DCs. (B) Incidence of contact. Incidence of interactions of various durations between BMDCs and OT-II CD4⁺ T cells at 10-minute intervals. Data are mean ± SD and are representative of 3 experiments. (C) The overall duration of DC–T-cell interaction is shown. Data points represent individual durations. *P < .05 vs corresponding B6 mice. (D) Temperature-dependent activity of acquired antigens with FITC-OVA in MHC class II⁺ DCs of B6 mice and mDia1^−/− mice. The activities of acquired antigens of DCs were observed by measuring the mean fluorescence intensity of ingested FITC at 4°C and 37°C for 45 minutes. Data are mean ± SD and are representative of 3 experiments.