Intracellular antibody-bound pathogens stimulate immune signaling via the Fc receptor TRIM21

Nat Immunol. 2013 Apr;14(4):327-36. doi: 10.1038/ni.2548. Epub 2013 Mar 3.


During pathogen infection, antibodies can be carried into the infected cell, where they are detected by the ubiquitously expressed cytosolic antibody receptor TRIM21. Here we found that recognition of intracellular antibodies by TRIM21 activated immune signaling. TRIM21 catalyzed the formation of Lys63 (K63)-linked ubiquitin chains and stimulated the transcription factor pathways of NF-κB, AP-1, IRF3, IRF5 and IRF7. Activation resulted in the production of proinflammatory cytokines, modulation of natural killer stress ligands and induction of an antiviral state. Intracellular antibody signaling was abrogated by genetic deletion of TRIM21 and was restored by ectopic expression of TRIM21. The sensing of antibodies by TRIM21 was stimulated after infection by DNA or RNA nonenveloped viruses or intracellular bacteria. Thus, the antibody-TRIM21 detection system provides potent, comprehensive activation of the innate immune system independently of known pattern-recognition receptors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenoviridae / immunology
  • Animals
  • Antibodies, Viral / chemistry
  • Antibodies, Viral / immunology*
  • Antibodies, Viral / metabolism
  • Antigen-Antibody Complex / immunology
  • Antigen-Antibody Complex / metabolism
  • Bacteria / immunology
  • Cell Line
  • Cross Reactions
  • Cytokines / biosynthesis
  • Humans
  • Inflammation Mediators / metabolism
  • Interferon Regulatory Factors / metabolism
  • Intracellular Space / immunology*
  • Intracellular Space / metabolism*
  • Mice
  • Molecular Docking Simulation
  • NF-kappa B / metabolism
  • Protein Binding
  • Protein Conformation
  • Protein Interaction Domains and Motifs
  • Receptors, Fc / metabolism*
  • Receptors, Pattern Recognition / metabolism
  • Ribonucleoproteins / chemistry
  • Ribonucleoproteins / immunology*
  • Ribonucleoproteins / metabolism
  • Signal Transduction*
  • Transcription Factor AP-1 / metabolism
  • Viruses / immunology*


  • Antibodies, Viral
  • Antigen-Antibody Complex
  • Cytokines
  • Inflammation Mediators
  • Interferon Regulatory Factors
  • NF-kappa B
  • Receptors, Fc
  • Receptors, Pattern Recognition
  • Ribonucleoproteins
  • SS-A antigen
  • Transcription Factor AP-1