Figure 4

Rhamnogalacturonan II (RG-II) interacts with Toll-like receptor 4 (TLR4). (a) Colocalization of RG-II and TLR4 on bone marrow-derived dendritic cells (BMDCs). BMDCs were treated with fluorescein isothiocyanate (FITC)-conjugated RG-II (0.5 mg ml⁻¹) for 30 min, and fixed and stained with anti-TLR4-PE-conjugated antibody overnight at 4 °C. Cell morphology and fluorescence intensity were analyzed using the Zeiss LSM510 Meta confocal laser scanning microscope. (b) CD14 and lipopolysaccharide-binding protein (LBP) are crucial for RG-II-mediated interleukin-12 (IL-12) production. BMDCs were pretreated with anti-CD14, anti-LBP and anti-IgG (1 μg ml⁻¹) for 30 min and then stimulated with RG-II (1 mg ml⁻¹) for 24 h. Cytokine concentrations in culture supernatants were measured in triplicate by enzyme-linked immunosorbent assay (ELISA). **Significant difference at P<0.01 compared with unstimulated cells. The results are representative of the three experiments performed.