Directional mast cell degranulation of tumor necrosis factor into blood vessels primes neutrophil extravasation

Immunity. 2021 Mar 9;54(3):468-483.e5. doi: 10.1016/j.immuni.2020.12.017. Epub 2021 Jan 22.


Tissue resident mast cells (MCs) rapidly initiate neutrophil infiltration upon inflammatory insult, yet the molecular mechanism is still unknown. Here, we demonstrated that MC-derived tumor necrosis factor (TNF) was crucial for neutrophil extravasation to sites of contact hypersensitivity-induced skin inflammation by promoting intraluminal crawling. MC-derived TNF directly primed circulating neutrophils via TNF receptor-1 (TNFR1) while being dispensable for endothelial cell activation. The MC-derived TNF was infused into the bloodstream by directional degranulation of perivascular MCs that were part of the vascular unit with access to the vessel lumen. Consistently, intravenous administration of MC granules boosted neutrophil extravasation. Pronounced and rapid intravascular MC degranulation was also observed upon IgE crosslinking or LPs challenge indicating a universal MC potential. Consequently, the directional MC degranulation of pro-inflammatory mediators into the bloodstream may represent an important target for therapeutic approaches aimed at dampening cytokine storm syndromes or shock symptoms, or intentionally pushing immune defense.

Keywords: blood vessel; contact hypersensitivity; degranulation; extravasation; inflammation; mast cell; neutrophil; tumor necrosis factor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blood Circulation
  • Blood Vessels / immunology*
  • Cell Degranulation
  • Cells, Cultured
  • Dermatitis, Contact / immunology*
  • Immune System Diseases
  • Inflammation / immunology*
  • Leukocyte Disorders
  • Mast Cells / immunology*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Neutrophil Activation
  • Neutrophils / immunology*
  • Receptors, Tumor Necrosis Factor, Type I / metabolism
  • Secretory Vesicles / metabolism
  • Skin / pathology*
  • Tumor Necrosis Factor-alpha / genetics
  • Tumor Necrosis Factor-alpha / metabolism*


  • Receptors, Tumor Necrosis Factor, Type I
  • Tumor Necrosis Factor-alpha

Supplementary concepts

  • Neutrophil Chemotactic Response, Abnormal