Blood Cells - Tissue Functioning and Remodeling in the Circulatory and Ventilatory Systems - page 99

Table 3.12. Mastocyte functions.

Activity Targets

Procedure

Recruitment and activation of Monocytes and macrophages

Release of lipid mediators - icosanoids
(prostaglandins, prostacyclins, thromboxanes,
and leukotrienes)
Dendritic cells
T lymphocytes
Basophils, eosinophils, and neutrophils

Phagocytosis
Alterations of

Epithelial tight junctions

Degradation of Toxins (by chymase and/or other peptidases)

Venoms (by carboxypeptidase-A)

Bactericidal activity Release cathelicidins and chymases

Defense against Some parasites

(innate and IgE-mediated acquired responses)
Viruses (via CD8 + T cells)

Fungi

3.8.2 Mastocyte Functions

Mastocytes contribute to both allergy initiation and early phase by releasing pro-
inflammatory mediators (histamine, tryptase, prostaglandins, and leukotrienes) and
late phase by liberating cytokines and chemokines that recruit inflammatory cells
(eosinophils, basophils, neutrophils, CD4 T cells, and macrophages).

Mastocytes also favors angiogenesis, as they produce growth factors, such
as vascular endothelial growth factor, fibroblast growth factor-2, platelet-derived
growth factor, transforming growth factor-

+

β , tumor-necrosis factor- α , granulocyte-

macrophage colony-stimulating factor, and interleukin-3 and -8.
Mastocytes possess features of acquired immunity cells: they phagocytize, and
process and present antigens to T lymphocytes and modulate T- and B-cell responses
such as lymphocyte growth, recruitment, and production of immunoglobulins (Table
3.12 ). Mastocytes express major histocompatibility complex class-1 molecules, and
are able to produce MHC class-2 molecules under some circumstances. Mastocytes
express receptor Fc R1 for immunoglobulin-E produced by B cells. Mastocytes

operate in acquired immunity against parasites and other pathogens, such as bacteria
and viruses in the gut and skin. Certain mastocytes are activated by IgG via Fc

γ

receptors (Table 3.13 ).