The degranulation process in a Mast cell. 1 = antigen; 2 = IgE; 3 = FcεRI; 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 antimicrobial cytotoxic molecules from secretory vesicles called granules found inside some cells. It is used by several different cells involved in the immune system, including granulocytes (neutrophils, basophils and eosinophils) and mast cells, and certain lymphocytes such as natural killer (NK) cells and cytotoxic T cells, whose main purpose is to destroy invading microorganisms.


Mast cells

Antigens interact with IgE molecules already bound to high affinity Fc receptors on the surface of mast cells to induce degranulation. The mast cell releases a mixture of compounds, including histamine, proteoglycans and serine proteases, from its cytoplasmic granules.[1]


In a similar mechanism, activated eosinophils release preformed mediators such as major basic protein, and enzymes such as peroxidase, following interaction between their Fc receptors and IgE molecules that are bound to large parasites like helminths.[2][3]


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 gelatinase granules, specific granules, and azurophil granules.[4] [5]

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.[6]

See also

External links


  1. ^ Yamasaki S, Saito T (2005). "Regulation of mast cell activation through FcepsilonRI". Chem Immunol Allergy. Chemical Immunology and Allergy 87: 22–31. doi:10.1159/000087568. ISBN 3-8055-7948-9. PMID 16107760. 
  2. ^ David J, Butterworth A, Vadas M (1980). "Mechanism of the interaction mediating killing of Schistosoma mansoni by human eosinophils". Am J Trop Med Hyg 29 (5): 842–8. PMID 7435788. 
  3. ^ Capron M, Soussi Gounni A, Morita M, Truong M, Prin L, Kinet J, Capron A (1995). "Eosinophils: from low- to high-affinity immunoglobulin E receptors". Allergy 50 (25 Suppl): 20–23. doi:10.1111/j.1398-9995.1995.tb04270.x. PMID 7677229. 
  4. ^ Faurschou M, Borregaard N (2003). "Neutrophil granules and secretory vesicles in inflammation". Microbes Infect 5 (14): 1317–1327. doi:10.1016/j.micinf.2003.09.008. PMID 14613775. 
  5. ^ Lominadze G, Powell D, Luerman G, Link A, Ward R, McLeish K (2005). "Proteomic analysis of human neutrophil granules". Mol Cell Proteomics 4 (10): 1503–1521. doi:10.1074/mcp.M500143-MCP200. PMID 15985654. 
  6. ^ Veugelers K, Motyka B, Frantz C, Shostak I, Sawchuk T, Bleackley R (2004). "The granzyme B-serglycin complex from cytotoxic granules requires dynamin for endocytosis". Blood 103 (10): 3845–3853. doi:10.1182/blood-2003-06-2156. PMID 14739229. 

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Look at other dictionaries:

  • Degranulation — Granula sind unter dem Mikroskop deutlich sichtbare, körnchenförmige Einlagerungen in biologischen Zellen, die meist Speicher oder Sekretstoffe enthalten (z. B. Glykogen , Lipid , Protein , Ferritin oder Pigment Granula). Sie lassen sich anhand… …   Deutsch Wikipedia

  • degranulation — noun Date: circa 1941 the process of losing granules; specifically the process by which cytoplasmic granules (as of mast cells) release their contents …   New Collegiate Dictionary

  • degranulation — Release of secretory granule contents by fusion with the plasma membrane …   Dictionary of molecular biology

  • degranulation — /dee gran yeuh lay sheuhn/, n. the loss or elimination of granules. [1940 45; DE + GRANULATION] * * * …   Universalium

  • degranulation — noun The loss of secretory granules in certain cells …   Wiktionary

  • degranulation — Disappearance or loss of cytoplasmic granules (lysosomes) from a cell. * * * de·gran·u·la·tion (.)dē .gran yə lā shən n the process of losing granules specif the process by which cytoplasmic granules (as of mast cells) release their contents… …   Medical dictionary

  • degranulation — de·granulation …   English syllables

  • dégranulation —  n.f. Biol. Processus de transformation des cellules …   Le dictionnaire des mots absents des autres dictionnaires

  • degranulation — (¦)dē, də̇ˌ noun Etymology: de + granulation : the process of losing granules ; specifically : the process by which cytoplasmic granules (as of mast cells) release their contents …   Useful english dictionary

  • basophil degranulation test — an in vitro procedure testing allergic sensitivity to a specific allergen at the cellular level by measuring staining of basophils after exposure to the allergen; a reduction in the number of granulated cells is a positive result …   Medical dictionary

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