CRIg signals induce anti-intracellular bacterial phagosome activity in a chloride intracellular channel 3-dependent manner

Eur J Immunol. 2013 Mar;43(3):667-78. doi: 10.1002/eji.201242997. Epub 2013 Jan 31.


Macrophages provide a first line of defense against bacterial infection by engulfing and killing invading bacteria, but intracellular bacteria such as Listeria monocytogenes (LM) can survive in macrophages by various mechanisms of evasion. Complement receptor of the immunoglobulin (CRIg), a C3b receptor, binds to C3b on opsonized bacteria and facilitates clearance of the bacteria by promoting their uptake. We found that CRIg signaling induced by agonistic anti-CRIg mAb enhanced the killing of intracellular LM by macrophages, and that this occurred in LM-containing phagosomes. Chloride intra-cellular channel 3 CLIC3, an intracellular chloride channel protein, was essential for CRIg-mediated LM killing by directly interacting with the cytoplasmic domain of CRIg, and the two proteins colocalized on the membranes of LM-containing vacuoles. CLIC3(-/-) mice were as susceptible to LM as CRIg(-/-) mice. These findings identify a mechanism embedded in the process by which macrophages take up opsonized bacteria that prevents the bacteria from evading cell-mediated killing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Chloride Channels / metabolism*
  • Chlorides / metabolism
  • Female
  • Humans
  • Listeria monocytogenes / immunology
  • Lysosomes / immunology
  • Lysosomes / metabolism
  • Macrophages / immunology*
  • Macrophages / metabolism*
  • Macrophages / microbiology
  • Male
  • Membrane Fusion / immunology
  • Mice
  • Phagocytosis / genetics
  • Phagocytosis / immunology
  • Phagosomes / immunology*
  • Protein Binding
  • Receptors, Complement / genetics
  • Receptors, Complement / metabolism*
  • Receptors, Complement 3b / genetics
  • Receptors, Complement 3b / immunology
  • Receptors, Complement 3b / metabolism*
  • Signal Transduction*
  • Vacuoles / immunology
  • Vacuoles / metabolism
  • Vacuoles / microbiology


  • Chloride Channels
  • Chlorides
  • ClC-3 channel
  • Receptors, Complement
  • Receptors, Complement 3b
  • VSIG4 protein, mouse