Medicine & USMLE

Natural Killer Cells

  1. Innate Immunity
  2. Adaptive Immunity
  3. Macrophages
  4. Neutrophils
  5. Dendritic Cells
  6. Mast Cells
  7. Eosinophils
  8. Basophils
  9. Natural Killer Cells
  10. Antigens
  11. MHC I and II
  12. Antibodies
  13. B Lymphocytes Overview
  14. B Cell Stages
  15. B-Cell Activation
  16. Plasma B-Cells
  17. Memory B-Cells
  18. T-Lymphocytes Overview
  19. T-Cell Stages
  20. Types of Activated T-Cells


NK cells, or natural killer cells, are lymphocytes of the innate immune system that work to directly kill abnormal cells. These abnormal cells usually express reduced amounts of MHC or major histocompatibility complex, which is a non-specific signal for viral infection or cancer.

Key Points

  • Natural Killer Cells (NK Cells)
    • Lymphocyte member of innate immune system
    • Kills abnormal cells (virus-infected or cancer)