Neutrophil Granules and Exocytosis Mechanisms

Neutrophil granules are membrane-bound organelles formed during granulopoiesis that store pre-formed antimicrobial proteins and enzymes. They are classically categorised into azurophilic (primary), specific (secondary) and gelatinase (tertiary) granules, each carrying distinct cargo such as myeloperoxidase, lactoferrin and gelatinase respectively. Upon activation by chemotactic or inflammatory stimuli, neutrophils undergo degranulation—a specialised form of exocytosis—whereby granules translocate, dock at the plasma membrane and fuse to release their contents. This process is regulated by intracellular signalling cascades including small GTPases, kinases and SNARE protein complexes that ensure selective mobilisation of granule subsets. Exocytosis of neutrophil granules drives microbial killing, oxidative burst and formation of extracellular traps, yet excessive or dysregulated release can lead to host tissue damage and chronic inflammation. Understanding these mechanisms provides avenues for targeted therapies that preserve host defence while limiting collateral injury.

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Neutrophil Granules and Exocytosis Mechanisms publication trend

The graph below shows the total number of articles in neutrophil granules and exocytosis mechanisms across all publications each year (not limited to Nature Index journals).

Technical terms

Neutrophil: A type of white blood cell central to innate immunity, responsible for rapid responses to infection.

Azurophilic granules: Primary neutrophil granules containing potent enzymes such as myeloperoxidase and elastase.

Specific granules: Secondary granules enriched in lactoferrin and components that support microbial opsonisation.

Exocytosis: The process by which intracellular vesicles fuse with the plasma membrane to secrete their contents.

SNARE proteins: A family of membrane-associated proteins that mediate vesicle docking and fusion during exocytosis.

Rab GTPases: Small guanosine triphosphatases that regulate vesicle trafficking and granule mobilisation within the cell.

References

1. Syntaxin-4 and SNAP23 are involved in neutrophil degranulation, but not in the release of mitochondrial DNA during NET formation. Frontiers in Immunology (2023).
2. Mechanisms of Degranulation in Neutrophils. Allergy, Asthma & Clinical Immunology (2006).
3. Proteomic Analysis of Human Neutrophil Granules* S. Molecular & Cellular Proteomics (2005).
4. Identification of Neutrophil Exocytosis Inhibitors (Nexinhibs), Small Molecule Inhibitors of Neutrophil Exocytosis and Inflammation DRUGGABILITY OF THE SMALL GTPase Rab27a*. Journal of Biological Chemistry (2016).