FIGURE 2.

S. aureus WTA is a functional ligand of human MBL. MBL/MASP complex (0.1 μg) were incubated at 4 °C for 2 h with immobilized ligands (5 μg) including WTA-free-PG [WTA(−)-PG], purified WTA, WTA-containing PG [WTA(+)-PG], or mannan. After washing of the unbound MBL/MASP complex, C4 (0.1 μg) was added and incubated at 37 °C for 1 h. Bound MBL (a) or C4 (b) was detected using mouse anti-human MBL mAb or mouse anti-human C4 mAb, respectively, with goat anti-mouse IgG (H+L) antibody conjugated with HRP and a substrate, 3,3′,5,5′-tetramethylbenzidine (450 nm). The results are representative of three independent experiments.