Bordetella pertussis virulence factors affect phagocytosis by human neutrophils

The interaction between human neutrophils and wild-type Bordetella pertussi s or mutants expressing altered lipopolysaccharide or lacking virulence fac tors-pertussis toxin, adenylate cyclase toxin, dermonecrotic toxin, filamen tous hemagglutinin (FEW), pertactin, or BrkA-was examined. In the absence o f antibodies, the wild-type strain and the mutants, with the exception of m utants lacking FHA, attached efficiently to neutrophils. The addition of op sonizing antibodies caused a significant reduction (approximately 50%) in a ttachment of the wild-type strain and most of the mutants expressing FI-W, suggesting that bacterium-mediated attachment is more efficient than Fc-med iated attachment. Phagocytosis was also examined. In the absence of antibod ies, about 12% of the wild-type bacteria were phagocytosed. Opsonization ca used a statistically significant reduction in phagocytosis (to 3%), possibl y a consequence of reduced attachment. Phagocytosis of most of the mutants was similar to that of the wild type, with the exception of the mutants lac king adenylate cyclase toxin. About 70% of the adenylate cyclase toxin muta nts were phagocytosed, but only in the presence of opsonizing antibody, sug gesting that Fc receptor-mediated signaling may be needed for phagocytosis. These studies indicate that FHA mediates attachment of B. pertussis to neu trophils, but adenylate cyclase toxin blocks phagocytosis.