Blood Cells - Tissue Functioning and Remodeling in the Circulatory and Ventilatory Systems - page 97

3.8 Mastocytes

Mastocytes, or mast cells, 82 are leukocytes that contain storage granules for
inflammatory mediators, such as histamine, serotonin, proteolytic enzymes cleaving
complement components, heparin, chondroitin sulfate, and chemotactic factors,
in particular for eosinophils and neutrophils. Mastocytes contribute to innate
and adaptive immunity, angiogenesis, wound healing, tissue remodeling, and
immunoregulation [ 190 ].
Mastocytes are tissue-resident sentinels. Differences in concentrations of stem
cell factor and other cytokines and chemokines (interleukins IL3, IL2, IL4, IL9, and
IL18 as well as chemokines CCL2 and CCL5), or nerve growth factor in respective
tissues, and possibly between different regions within the same tissue, can determine
the number, distribution, and subtype of mastocytes at these loci. Mastocytes recruit
many immunocyte types (granulocytes, monocytes, macrophages, dendritic cells,
B-, T-, and NK cells; Table 3.11 ).

Table 3.11. Immunomodulatory mastocytes (Source: [ 191 ]; IL: interleukin; PG: prostaglandin:
TNF: tumor-necrosis factor; TSLP: thymic stromal lymphopoietin). Mastocytes initiate and
increase magnitude and/or duration of immune response (positive activity). They promote the
initiation and augment the magnitude of inflammation and tissue remodeling, as well as tissue
reaction during allergic and autoimmune disorders. Mastocytes also have anti-inflammatory and
immunosuppressive (negative) activity. Mastocytes can first enhance and later limit certain innate
and adaptive immune responses.

Positive functions Negative effects

Maturation, differentiation, and Suppression of cytokine production

recruitment of immunocytes by T cells, monocytes, and

(via chemokines, histamine, keratinocytes

leukotriene-B4, TNF, and peptidases) (via IL10)

Antigen presentation to T cells Enhancement of dendritic

Production of IgE by B cells cell-mediated decrease of

(via IL4, IL13, and TNFSF5) T-cell proliferation and cytokine

production (via IL10)

Helper-2 T-cell responses (via PGd2
on maturation of dendritic cells)

Expression of TSLP by epithelial cells
(via TNF, IL4, and IL13)

Production of chemo- and cytokines by
airway smooth myocytes
(via TNF, IL4 and IL13)

82 Mastocytes were first described with some details by P. Ehrlich in 1878.