SUMMARY: The effect of secreted virulence components of on chemiluminescence (CL) of rabbit peritoneal neutrophils was determined with the chemotactic peptide N’-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP) or intact as the stimulus. Pertussis toxin (PT) inhibited the response to fMLP in a dose-dependent manner, although only after the neutrophils had been exposed to the toxin for >15 min. Both filamentous haemagglutinin (FHA) and lipopolysaccharide (LPS) markedly enhanced the CL response to fMLP after ≥15 min incubation with the neutrophils. Similar effects to those of LPS were also seen with smooth and rough LPS from . With the lowest dose of each component which elicited a maximal effect on CL, the inhibitory effect of PT overrode the enhancing effect of FHA and LPS. Pre-incubation of neutrophils with PT, FHA or B. pertussis LPS caused a slight reduction in the subsequent CL response to virulent Tohama. Virulent (phase I, or X-mode) organisms of 18334 and Tohama induced greater neutrophil CL than their avirulent (C-mode) derivatives. There appeared to be an inverse correlation between bacterial hydrophilicity and the ability to induce neutrophil CL: X-mode bacteria were significantly less hydrophilic than C-mode organisms. Three mutants, the adenylate cyclase (AC)- and haemolysin (HLY)-deficient BP348, the FHA-deficient BP353, and the PT-deficient BP357, generated similar levels of CL and had similar hydrophilicity values. The hydrophilicity value of the avirulent mutant BP347 (deficient in AC, HLY, FHA and PT) and the CL induced by this strain were similar to those of C-mode organisms. Thus, the interaction of with neutrophils appears to be complex, reflecting both the alteration of leucocyte function by secreted virulence components of the organism and, in the absence of opsonins, the surface properties of the bacterium.


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