Degranulation

Source: Wikipedia, the free encyclopedia.
IgE; 3 = FcεR1; 4 = preformed mediators (histamine, proteases, chemokines, heparin); 5 = granules; 6 - Mast cell; 7 - newly formed mediators (prostaglandins, leukotrienes, thromboxanes, platelet-activating factor
)

Degranulation is a cellular process that releases

granulocytes (neutrophils, basophils, eosinophils, and mast cells). It is also used by certain lymphocytes such as natural killer (NK) cells and cytotoxic T cells
, whose main purpose is to destroy invading microorganisms.

Mast cells

Degranulation in mast cells is part of an inflammatory response, and substances such as histamine are released. Granules from mast cells mediate processes such as "vasodilation, vascular homeostasis, innate and adaptive immune responses, angiogenesis, and venom detoxification."[1]

IgE molecules already bound to high affinity Fc receptors on the surface of mast cells to induce degranulation, via the activation of tyrosine kinases within the cell. The mast cell releases a mixture of compounds, including histamine, proteoglycans, serotonin, and serine proteases from its cytoplasmic granules.[2]

Eosinophils

In a similar mechanism, activated eosinophils release preformed mediators such as

helminths.[3][4]

Neutrophils

Degranulation in neutrophils can occur in response to infection, and the resulting granules are released in order to protect against tissue damage. Excessive degranulation of neutrophils, sometimes triggered by bacteria, is associated with certain inflammatory disorders, such as asthma and septic shock.[5][6]

Four kinds of granules exist in neutrophils that display differences in content and regulation. Secretory vesicles are the most likely to release their contents by degranulation, followed by

azurophil granules.[7]
[8]

Cytotoxic T cells and NK cells

Cytotoxic T cells and NK cells release molecules like

perforin and granzymes
by a process of directed exocytosis to kill infected target cells.[9]

See also

References

  1. PMID 26779180
    .
  2. PMID 16107760
    .
  3. PMID 7435788
    .
  4. S2CID 36197719
    .
  5. PMID 34017259
    .
  6. PMID 20525154
    .
  7. PMID 14613775
    .
  8. PMID 15985654.[permanent dead link
    ]
  9. S2CID 23814556
    .

External links
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