TLR signaling fine-tunes anti-influenza B cell responses without regulating effector T cell responses

J Immunol. 2007 Feb 15;178(4):2182-91. doi: 10.4049/jimmunol.178.4.2182.

Abstract

Influenza is a ssRNA virus that has been responsible for widespread morbidity and mortality; however, the innate immunological mechanisms that drive the adaptive anti-influenza immune response in vivo are yet to be fully elucidated. TLRs are pattern recognition receptors that bind evolutionarily conserved pathogen-associated molecular patterns, induce dendritic cell maturation, and consequently aid the development of effective immune responses. We have examined the role of TLRs in driving effective T and B cell responses against influenza virus. We found TLR3 and its associated adapter molecule, Toll/IL-R domain-containing adaptor-inducing IFN-beta, did not play a role in the development of CD4(+) or CD8(+) T cell responses against influenza virus, nor did they influence influenza-specific B cell responses. Surprisingly, TLR7 and MyD88 also played negligible roles in T cell activation and effector function upon infection with influenza virus; however, their signaling was critical for regulating anti-influenza B cell Ab isotype switching. The induction of appropriate anti-influenza humoral responses involved stimulation of TLRs on B cells directly and TLR-induced production of IFN-alpha, which acted to reduce IgG1 and increase IgG2a/c class switching. Notably, direct TLR signaling on B cells or T cell help through the CD40-CD40L interaction was sufficient to support B cell proliferation and IgG1 production, whereas IFN-alpha was critical for fine-tuning the nature of the isotype switch. Taken together, these data reveal that TLR signaling is not required for anti-influenza T cell responses, but through both direct and indirect means orchestrates appropriate anti-influenza B cell responses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Viral / immunology
  • Antibody Formation / immunology
  • B-Lymphocytes / immunology*
  • CD4-Positive T-Lymphocytes / immunology*
  • CD40 Antigens / immunology
  • CD40 Ligand / immunology
  • CD8-Positive T-Lymphocytes / immunology*
  • Cell Proliferation
  • Dendritic Cells / immunology
  • Humans
  • Immunoglobulin Class Switching / immunology
  • Immunoglobulin G / immunology
  • Influenza A Virus, H1N1 Subtype / immunology*
  • Influenza, Human / immunology*
  • Interferon-alpha / immunology
  • Interferon-beta / immunology
  • Membrane Glycoproteins / immunology*
  • Mice
  • Mice, Knockout
  • Myeloid Differentiation Factor 88 / immunology
  • Signal Transduction / immunology
  • Toll-Like Receptor 3 / immunology*
  • Toll-Like Receptor 7 / immunology*

Substances

  • Antibodies, Viral
  • CD40 Antigens
  • Immunoglobulin G
  • Interferon-alpha
  • Membrane Glycoproteins
  • Myd88 protein, mouse
  • Myeloid Differentiation Factor 88
  • Tlr7 protein, mouse
  • Toll-Like Receptor 3
  • Toll-Like Receptor 7
  • CD40 Ligand
  • Interferon-beta