Medicine & USMLE


  1. TNF-alpha
  2. IL-1
  3. IL-2
  4. IL-3
  5. IL-4
  6. IL-5
  7. IL-6
  8. IL-8
  9. IL-10
  10. IL-12
  11. TGF-beta
  12. IFN-alpha and IFN-beta
  13. IFN-gamma


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