IFN-gamma

Summary

Interferon-gamma (IFN-γ), also known as a type 2 interferon, is a cytokine that is critical for fighting viral infections. Produced by Th1 cells and Natural Killer (NK) cells, IFN-gamma activates macrophages to kill infected cells. Activating macrophages also helps amplify the immune response since macrophages themselves stimulate Th1 cells by producing interleukin-12 (IL-12), which in turn produce more IFN-gamma. Finally, IFN-gamma increases MHC expression in all cells, increasing antigen presentation, which helps to mount a larger adaptive immune response by T-cells. 

Key Points

• Interferon-gamma (IFN-gamma)
  • Also known as type 2 interferon
  • Secreted by Th1 cells and Natural Killer (NK) cells
  • Actions
    • Activates Macrophages
      • Increases phagocytosis and antigen presentation
      • Involved in pathogenesis of granuloma
      • Creates a reinforcing feedback loop, since macrophages produce Interleukin-12 to stimulate Th1 cells
    • Increases MHC expression
      • Increases antigen presentation by all cells