Complement component C3 deposition on K pneumoniae strains facilitated by O-specific polysaccharide antibodies is shown. Purified immunoglobulins from the same plasma samples in (A), including HCP and P from patients with K pneumoniae bloodstream infection were used. Following opsonisation with both untreated and adsorbed immunoglobulins (with O1v1-EPA, O3b-EPA, and EPA), GPC was added. The subsequent C3 deposition on both wild type and ΔwcaJ K pneumoniae strains was measured and is presented as MFI divided by 1000, on the y-axis (n=5). EPA=exoprotein A of Pseudomonas aeruginosa. GPC=guinea pig complement. HCP=pooled healthy control plasma. HSA=human serum albumin. K pneumoniae=Klebsiella pneumoniae. MFI=median fluorescence intensity. P=plasma sample.
