Commentary Cellscience Reviews Vol 3 No 2 ISSN 1742-8130

Mast Cells Dampen Immune Reactions against Transplants
- An Ever Growing List of Their Functions

Mast cells are present at the body’s interface with the environment in locations such as the skin, gastrointestinal tract, airway, and vasculature. Arising from multipotent hematopoietic progenitors in bone marrow, mast cells normally do not mature before leaving the bone marrow, but instead circulate through the vascular system as immature progenitors that then complete their development peripherally within connective or mucosal tissues (Okayama & Kawakami, 2006). These cells have been most extensively characterized as effectors of allergic reactions. Evidence has been generated that shows the essential or contributing role of mast cells in anaphylaxis and asthma (Kawakami & Galli, 2002). Indeed, mast cells activated by IgE and antigen or other stimuli secrete preformed and de novo synthesized proinflammatory mediators such as histamine, serotonin, proteases, prostaglandins, leukotrienes, cytokines, chemokines, free radicals, and so on (Galli et al., 2005; Metcalfe et al., 1997). Studies in the 80’s and 90’s have extended our understanding of the role of mast cells in the defense against certain parasites and bacteria. Recently, mast cells were also shown to contribute to resistance against venoms produced by snakes and honeybees (Metz et al., 2006). In addition to controlling the attack from pathogens or toxins, mast cells are required for efficient autoimmune reactions: without mast cells animals have less inflammation upon the induction of experimental autoimmune encephalomyelopathy (Secor et al., 2000) and rheumatoid arthritis (Lee et al., 2002).

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