Mast Cells

Question 1

mMCP-1 and mMCP-2

Answer 1

Expressed exclusively in murine gut mucosa mast cells

Question 2

Mast cell development in mucosal epithelia is ___-dependent where as it is independent in other locations.

Answer 2

Mast cell development in mucosal epithelia is T cell-dependent where as it is independent in other locations.

Question 3

Mast cell development

Answer 3

Originate in bone marrow. Arise from a CD34+ / cKit+ / FcεRIα+ mast cell progenitor. Differentiation is SCF and IL-3 dependent.

Question 4

β₇ integrin

Answer 4

Provides selective gut-homing transmigration

Question 5

IL-9 in mast cells

Answer 5

Stimulates histamine synthesis and granule development, as well as upregulating mMCP-1 and mMCP-2.

Question 6

IL-4 in mast cells

Answer 6

Upregulates LTC₄ Synthase, which then results in enhanced SCF-dependent proliferation via autocrine cys-LT signaling downstream of LTC₄.

This occurs via CysLT₁R

Question 7

Microphthalmia transcription factor (MITF)

Answer 7

Controls c-kit transcription in mast cells, as well as the expression of several proteases and hematopoietic prostaglandin D₂ synthase (H-PGDS)

Question 8

GATA-1 and GATA-2

Answer 8

GATA-1 promotes FcεRI α and β chains in mast cells.

GATA-2 is vital for embryonic mast cell development.

Question 9

Major Mast Cell Transcription Factors

Answer 9

GATA-1

GATA-2

MITF

PU.1

Question 10

Cromolyn

Answer 10

Prevents the release of acute inflammatory mediators (histamine, leukotrienes, prostaglandins) from mast cells, T cells, and eosinophils. Mechanism of action is poorly understood, but it may act by inhibiting calcium flux.

Perscribed for inflammatory diseases ranging from asthma to ulcerative colitis.

Question 11

Mast cells are required for protective neutrophilia responses to ____.

Answer 11

Mast cells are required for protective neutrophilia responses to Gram-negative peritoniteal and lung infection.

Question 12

Mediators of Mast Cell Activation and Degranulation

Answer 12

FcεRI crosslinking

FcγRIII crosslinking

C3a/C5a GPCR binding

CysLT₁R binding

A3 receptor binding (adenosine)

T1/ST2 binding by IL-33

TSLPR binding (Thymic stromal lymphopoietin)

Question 13

(Endogenous) Mediators of Mast Cell Inhibition

Answer 13

FcγRIIb crosslinking

Leukocyte immunotyrosine-like receptor B4 (LILRB4)

CD300a

β₂ adrenoreceptor

EP₂ Receptor (Prostaglandin E₂)

A2B receptor (adenosine)

Question 14

Mast cell mediators associated with anaphylaxis

Answer 14

Histamine

LTD₄

LTC₄

PGD₂

Question 15

Mastocytoma

Answer 15

Cutaneous mastocytosis that is limited to one region

Question 16

Urticaria pigmentosa

Answer 16

Brown-to-tan, flat lesions. May be caused by generalized cutaneous mastocytosis.

Displays Darier’s Sign: lesions swell with gentle pressure.

Question 17

Blockade of the ____ histamine receptor prevents the effects of mast cell-mediated allergic effects.

Answer 17

Blockade of the H1 histamine receptor prevents the effects of mast cell-mediated allergic effects.

Question 18

How PGE₂ prevents mast cell degranulation

Answer 18

EP₂ binding -> Gs activation -> Adenylyl cyclase -> cAMP -> PKA

PKA antagonizes calcium-dependent degranulation through an as of yet undiscovered mechanism