Bordetella pertussis Filamentous Hemagglutlnln Interacts with a Leukocyte Signal Transduction Complex and Stimulates Bacterial Adherence

Bordetella pertussis, the causative agent of whooping cough, adheres to human monocytes/macrophages by means of a bacterial surface-associated protein, filamentous hemagglutinin (FHA) and the leukocyte integrin, complement receptor 3 (CR3, ~xmfl2, CDllb/CD18). We show that an FHA Arg-Gly-Asp site induces enhanced R pertussis binding to monocytes, and that this enhancement is blocked by antibodies directed against CR3. Enhancement requires a monocyte signal transduction complex, composed of leukocyte response integrin (a~/33) and integrinassociated protein (CD47). This complex is known to upregulate CR3 binding activity. Thus, a bacterial pathogen enhances its own attachment to host cells by coopting a host cell signaling pathway.