HBEC take up fluorescently labelled antigen via actin-dependent mechanisms and form conjugates with T cells.

<p>Flow cytometry histograms depicting level of uptake of FITC-OVA (<i>A</i>) and Lucifer yellow (<i>C</i>) by HBEC at 37°C (blue line) vs background uptake at 4°C (red line). Data are representative of three independent experiments. Inhibition of FITC-OVA (<i>B</i>) and Lucifer yellow (<i>D</i>) uptake by HBEC cells pre-incubated with 10 mM Cytochalasin D (CCD). <i>C</i>, Flow cytometry histogram depicting level of uptake of Lucifer yellow by HBEC at 37°C (blue line) vs background uptake at 4°C (red line). Data are representative of three independent experiments Percentage increase in mean fluorescence intensity (MFI) is calculated as follows: (MFI following uptake at 37°C/MFI following uptake at 4°C)×100. Data are pooled from three independent experiments (n = 3 per experiment) and are expressed as mean +/− SD. ** and *** indicates statistically significant differences between control and CCD treatment as assessed by Student t test (p, 0.001, p<0.001 respectively). Representative flow cytometry plots indicating the levels of conjugation between HBEC and CD4⁺<i>(E)</i> and CD8⁺<i>(F)</i> cells. HBEC were labeled with PKH67 and isolated T cells labeled with PKH26 and equal numbers of cells were co-cultured for 30 min prior to flow cytometric analysis.