Blood Cells - Tissue Functioning and Remodeling in the Circulatory and Ventilatory Systems - page 100

Table 3.13. Mastocyte activating signals in innate and adaptive immunity (Source: [ 19 3 ]).

Molecule Receptor

Lipopolysaccharide Toll-like recptor TLR4

Peptidoglycan Toll-like recptor TLR2

Complement CR1, CR2, CR3, C3aR, C5aR

Endothelin-1 ET A

ε

IgE Fc R1

γ

IgG1 Fc R3

Parasites Fc ε R1 (via IgE)

Bacteria and their products CD48; Toll-like recptor TLR2, -4, -6, and -9

Double-stranded viral RNA Toll-like recptor TLR3

Single-stranded viral RNA Toll-like recptor TLR7

Venoms G proteins

3.8.3 Mastocyte Production and Types

Mastocytes produce many mediators that positively or negatively regulate the fate
and function of immunocytes [ 191 ]. Mastocytes promote recruitment of immuno-
cytes via secretion of tumor-necrosis factor and histamine.
Histamine elicits helper-1 T-cell activation via H 1 receptor, but suppresses both
T H1 -andT H2 -cell activation via H 2 receptor.
Mastocytes release cytokines that influence polarization and function of T-
cell subsets. Interleukins IL4, IL5, IL6, and IL13 and TNFSF5 can affect B-cell
development and function (e.g., IgE production). Mastocyte-derived IL10 increases
the ability of dendritic cells to prevent T-cell proliferation and cytokine production
and directly inhibits the production of prostanoids by neutrophils and inflammatory
cytokines by macrophages.
Long-lived mastocytes experience multiple cycles of de- and regranulation. Two
types of mastocytes include T and CT phenotypes according to mastocyte content:
either tryptase alone ( T mastocyte) or chymase and tryptase ( CT mastocyte), respec-
tively. Both subtypes coexist. Multiple molecules are released into the extracellular
medium (Tables 3.14 to 3.16 ).

3.8.3.1 Mastocytes of the Genital Tract

In the genital tract, mastocytes are activated by estrogens and lutenizing hormone,
as well as corticotropin-releasing hormone, endothelin-1, and substance-P [ 195 ].
Mastocytes are the main source of inducible nitric oxide synthase in the uterus.