FIG. 6.

Effect of PspA on C3 deposition via the classical pathway triggered by anticapsule MAb. WU2 (PspA⁺) and JY1119 (PspA⁻) were pretreated with different amounts of anticapsule MAb, washed, and then incubated with 10% FB^−/− (A) or WT (FB^+/+) (B) serum diluted with GVB²⁺. The data are representative of three experiments. (C) The amount of anticapsule MAb bound on PspA⁺ and PspA⁻ strains. WU2 (PspA⁺) and JY1119 (PspA⁻) were incubated with different dilutions of anticapsule MAb, and the surface binding of MAb was detected with Fluorescein isothiocyanate-conjugated goat anti-mouse IgG. Error bars indicate the standard errors of duplicate samples.