Figure 4.

C5a-mediated neutrophil defects are not restricted to phagocytosis. (A) Production of superoxide radical by neutrophils primed with 100 nM platelet-activating factor (PAF) and stimulated with 100 nM formyl methionyl leucyl phenylalanine (fMLP). P = 0.0076 by Mann-Whitney test. Data are derived from 16 patients and 12 matched volunteers, reflecting consecutive subjects recruited after interim analysis suggesting an effect of C5a on phagocytosis. (B) Correlation between PAF/fMLP-stimulated superoxide production by neutrophils and serum C3a concentrations in patients and matched volunteers. r and P values by Spearman’s correlation. Data are derived from 20 consecutive study participants (i.e., recruited after interim analysis suggesting an effect of C5a on phagocytosis). (C) Transmigration of neutrophils across a polystyrene membrane (pore size, 3 μm) to a target of 100 nM fMLP. Neutrophils from healthy volunteers were preincubated in control medium, or 100 nM C5a, **P = 0.008 by Mann-Whiney test (duplicates from n = 5 healthy peripheral blood neutrophil [PBN] donors). (D) Effect of C5a on the bactericidal capacity of neutrophils. P. aeruginosa strain PA01 was added for 30 minutes to wells containing no cells (left column), or to healthy neutrophils preincubated with either 100 nM C5a (middle column) or control medium (right column). Residual bacteria were quantified and expressed as colony-forming units (CFU) above those at t₀.**P = 0.003 by Mann-Whitney (duplicates of n = 5 healthy PBN donors).