Role of complement in mouse macrophage binding of Haemophilus influenzae type b. Academic Article uri icon

Overview

abstract

  • Previous in vivo studies demonstrated that clearance of encapsulated Haemophilus influenzae from blood is associated with the deposition of C3 on these bacteria and is independent of the later complement components (C5-C9). Since clearance of encapsulated bacteria is determined by phagocytosis of bacteria by fixed tissue macrophages, we studied the interaction of H. influenzae type b with macrophages in vitro. Organisms bound to macrophages in the presence of nonimmune serum. Binding was not evident in heat-treated serum or in serum from complement depleted animals and was inhibited by F(ab')2 fragments of antibody to C3 and by blockade of the macrophage complement receptor type 3. The majority of organisms bound in the presence of complement alone remained extracellular. Antibody in the form of convalescent serum or an IgG1 monoclonal to type b capsule did not increase the total number of organisms associated with macrophages, but did increase the number of organisms ingested. Furthermore, complement enhanced antibody-mediated ingestion. This in vitro study demonstrates that complement largely mediates binding of H. influenzae to macrophages. This binding may be critical in determining the early clearance of these bacteria from blood and may be an important mechanism of defense in the nonimmune, as well as the immune host.

publication date

  • January 1, 1990

Research

keywords

  • Complement System Proteins
  • Haemophilus influenzae
  • Macrophages
  • Phagocytosis

Identity

PubMed Central ID

  • PMC296407

Scopus Document Identifier

  • 0025169630

Digital Object Identifier (DOI)

  • 10.1172/JCI114414

PubMed ID

  • 2295697

Additional Document Info

volume

  • 85

issue

  • 1