Medicine & USMLE

Neutrophils - Granules

Other Cell Types
  1. Neutrophils - Overview
  2. Neutrophils - Granules
  3. Neutrophils - Oxidative Burst
  4. Basophils
  5. Eosinophils
  6. Mast Cells
  7. Monocytes / Macrophages
  8. Natural Killer (NK) Cells
  9. Dendritic Cells


The granules of neutrophils contain many compounds essential for proper neutrophil function. These molecules include myeloperoxidase or MPO, elastase, lysozyme, NADPH oxidase and lactoferrin. NADPH Oxidase and Myeloperoxidase both play important roles in the oxidative burst  of neutrophils, catalyzing the production of reactive oxygen species that are toxic to pathogens. Lysozyme breaks down the walls of bacteria, inducing cell death, while lactoferrin sequesters free iron to slow down bacterial growth. Lastly, elastase works to aid wound healing and tissue remodeling.

Key Points

  • Neutrophil Granules
    • Degranulation releases contents of these granules
    • Primary (azurophilic) granules
      • Myeloperoxidase (MPO)
      • Elastase
        • Protease involved in wound healing and tissue remodeling
        • Unchecked elastase activity leads to lung damage (emphysema) in alpha-1-antitrypsin deficiency
    • Secondary (specific) granules
      • Lysozyme
        • Breaks down peptidoglycan cell walls of bacteria
      • NADPH oxidase
      • Lactoferrin
        • Antimicrobial activity by sequestering free iron
      • Other hydrolytic enzymes