FIG. 3.

Opsonic killing of nonacetylated or acetylated mucoid P. aeruginosa strains in the presence of a nonopsonic monoclonal antibody (MAb), nonopsonic antibody to MEP in a normal human serum sample, and nonopsonic antibody in pooled sera from mice immunized with a high dose (50 μg) of MEP. Bars represent mean CFU killed, and error bars show the standard deviation. The percentage of the two nonacetylated strains killed by each of the three antibodies was significantly higher than the percentage of the acetylated strains killed by the corresponding antibodies (P < 0.001, as determined by ANOVA and Fisher's PLSD test for pairwise comparisons). C′, complement.