Complement component C3 promotes T-cell priming and lung migration to control acute influenza virus infection

Nat Med. 2002 Apr;8(4):373-8. doi: 10.1038/nm0402-373.


The complement cascade defines an important link between the innate and the specific immune system. Here we show that mice deficient for the third component of complement (C3-/- mice) are highly susceptible to primary infection with influenza virus. C3-/- mice showed delayed viral clearance and increased viral titers in lung, whereas mice deficient for complement receptors CR1 and CR2 (Cr2-/- mice) cleared the infection normally. Priming of T-helper cells and cytotoxic T cells (CTLs) in lung-draining lymph nodes was reduced, and the recruitment into the lung of virus-specific CD4+ and CD8+ effector T cells producing interferon-gamma was severely impaired in C3-/- but not in Cr2-/- mice. Consequently, T-helper cell-dependent IgG responses were reduced in C3-/- mice but remained intact in Cr2-/- mice. These results demonstrate that complement induces specific immunity by promoting T-cell responses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Viral / biosynthesis
  • Cell Movement / immunology
  • Complement C3 / deficiency
  • Complement C3 / genetics
  • Complement C3 / physiology*
  • Immunoglobulin G / biosynthesis
  • Interferon-gamma / biosynthesis
  • Lung / immunology*
  • Lung / pathology*
  • Lymphocyte Activation
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Orthomyxoviridae / immunology
  • Orthomyxoviridae Infections / immunology*
  • Orthomyxoviridae Infections / pathology*
  • Receptors, Complement 3b / deficiency
  • Receptors, Complement 3b / genetics
  • Receptors, Complement 3b / physiology
  • Receptors, Complement 3d / deficiency
  • Receptors, Complement 3d / genetics
  • Receptors, Complement 3d / physiology
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / pathology
  • T-Lymphocytes / physiology*
  • T-Lymphocytes, Cytotoxic / immunology
  • T-Lymphocytes, Helper-Inducer / immunology


  • Antibodies, Viral
  • Complement C3
  • Immunoglobulin G
  • Receptors, Complement 3b
  • Receptors, Complement 3d
  • Interferon-gamma