Fig. 4.

Receptor cross-linking activates TLR3. (A) Intracellular and surface expression of TLR3 in stable reporter cell lines, as assessed by FACS; shaded histograms are isotype controls. (B) TLR3-mediated activation of NF-κB in reporter cells by dsRNA (139 bp, 5 μg/ml) or polyI:C (1 μg/ml) and inhibition by bafilomycin. (C) TLR3 activation after cross-linking at the cell surface with anti-TLR3 polyclonal antibodies (pAb). (D) Cells preincubated in bafilomycin (baf) were activated by anti-TLR3 pAb (0.1 μg/ml) but not by dsRNA (as in B). Experiments were performed in triplicate, and error bars indicate one standard deviation.