FIG 2.

The lectin activity of langerin facilitates IAV infection of Lec2-Lg cells. (A) Binding of 10 μg/ml of BJx109 was determined by flow cytometry. (i) Representative histograms of BJx109 binding to CHO-ctrl, Lec2-ctrl, and Lec2-Lg cells in the presence of 20 mM Ca²⁺ (black histograms) or 5 mM EDTA (gray histograms). Unstained cells were included as a negative control (white histograms). (ii) The geometrical mean from triplicate samples of BJx109 binding to cells in the presence of 20 mM Ca²⁺ (black bars) or 5 mM EDTA (gray bars). Unstained cells (white bars) are shown for comparison. (B) Infection of Lec2-Lg cells is blocked by mannan but not by pretreatment of cells with bacterial sialidase. Monolayers of CHO-ctrl, Lec2-ctrl, and Lec2-Lg cells were treated with either 10 mg/ml mannan at 37°C for 30 min (Mn; stippled bars) or with 50 mU/ml of bacterial sialidase from Vibrio cholerae (Sial; black bars) at 37°C for 60 min prior to infection or incubated with serum-free medium alone (mock; white bars) before infection with 10⁷ PFU of BJx109. The percentage of infected cells was determined by using immunofluorescence at 6 to 8 h postinfection. ***, P < 0.001; n.s., not significant.