Cells Involved in Immune Responses 2018-2020 Flashcards
1. IgE binds to which subunit of FcRI? A. Alpha B. Beta C. Epsilon D. Gamma
- A, Alpha, p. 233.
FcRI is a tetrameric structure consisting of an alpha chain that binds IgE, a beta-chain signaling subunit and two gamma subunits that exist as immunoreceptor tyrosine-based activation Motif (ITAM) – containing homodimer signaling subunit
Chapter 14: Biology of Mast Cells and Their Mediators
Middleton’s Allergy Principles and Practice, 8th ed.
2. What is the best marker of systemic mast cell activation in anaphylaxis? A. α-tryptase B. β−tryptase C. Chymase D. Plasma histamine
- B Beta−tryptase, p. 237.
The best marker of systemic mast cell activation in anaphylaxis is an acute rise in the concentration of beta-tryptase in the peripheral circulation. Alpha tryptase is released by mast cells constitutively, beta-tryptase is stored in mast cell granules and released after IgE-dependent activation. Histamine concentrations in blood peak within 5 minutes, the tryptase concentration is maximal between 15 and 120 minutes after the onset of symptoms.
Chapter 14: Biology of Mast Cells and Their Mediators
Middleton’s Allergy Principles and Practice, 8th ed.
3. The Early Asthmatic Reaction is a decline in respiratory function within how many minutes of bronchial allergen challenge? A. 10-20 B. 60-90 C. 90-180 D. 240
- A, 10-20 minutes, p 239.
The early asthmatic response is a rapid deterioration of pulmonary function, as indicated by a fall in forced expiratory volume in 1 second, at 10 to 20 minutes following bronchial allergen challenge.
Chapter 14: Biology of Mast Cells and Their Mediators
Middleton’s Allergy Principles and Practice, 8th ed.
4. Which is an obligate mast cell growth factor? A. G-CSF B. GM-CSF C. SCF D. VEGF
- C, SCF, p 228.
Stem cell factor (SCF), or kit ligand, is an obligate mast cell growth factor that is derived from many cellular sources. Removal of SCF leads to rapid mast cell apoptosis. SCF is the ligand for kit
encoded by the proto-oncogene c-kit.
Chapter 14: Biology of Mast Cells and Their Mediators
Middleton’s Allergy Principles and Practice, 8th ed.
5. The arachidonic acid metabolite prostaglandin D2 (PGD2) is synthesized by which pathway? A. Cyclooxygenase B. IRAK C. Lipoxygenase D. Pyruvate
- A, Cyclooxygenase, p 233.
Newly formed metabolites of arachidonic acid are released from mast cells after IgE-dependent activation. The cyclooxygenase pathway produces PGD2, whereas the lipoxygenase
pathway forms Leukotriene C4 (LTC4).
Chapter 14: Biology of Mast Cells and Their Mediators
Middleton’s Allergy Principles and Practice, 8th ed.
- The generation of IP3 following IgE dependent mast cell stimulation leads to:
A. activation of the NOD2 pathway.
B. activation of the sodium calcium transporter on the rough endoplasmic reticulum.
C. Ca2+ mobilization from the rough endoplasmic reticulum and influx of extracellular Ca2+
D. efflux of intracellular Ca2+ and storage of Ca2+ in the rough endoplasmic reticulum.
- A, activation of the NOD2 pathway, p. 234.
IgE receptor activation initiates receptor aggregation with lipid rafts containing Lyn. Lyn kinase transphosphorylates tyrosine residues on the ITAMS binding to phosphorylated Fc(epsilon)R(beta)1 ITAM through the Src homology 2 domain. Syk protein tyrosine kinases are recruited to the rafts and bind the phosphorylated ITAMS. They are then phosphorylated to recruit Lyn and Syk promoting an activation loop. This results in fully activated Syk, starting a cascade that activates inositol triphosphate (IPs). IP3 induced Ca 2+ mobilization from the rough endoplasmic reticulum stores which initiates influx of extracellular Ca2+, a critical requirement for the release of preformed and newly generated mediators.
Chapter 14: Biology of Mast Cells and Their Mediators
Middleton’s Allergy Principles and Practice, 8th ed.
7. Mast cells are thought to skew T cell development towards which phenotype? A. Th1 B. Th2 C. Th17 D. Treg
- B, Th2, p. 237.
Rat mast cells can skew T cell differentiation towards a Th2 phenotype through IL-4 release. Mast cells also influence the development of dendritic cells and their ability to activate T
cells. Histamine increases IL-10 and decreases IL-12 production by mature dendritic cells, polarizing naïve T cells towards a Th2 phenotype.
Chapter 14: Biology of Mast Cells and Their Mediators
Middleton’s Allergy Principles and Practice, 8th ed.
8. Anaphylaxis is primarily mediated by A. eosinophils and basophils. B. mast cells and basophils. C. mast cells and eosinophils. D. neutrophils and eosinophils.
- A, mast cells and basophils, p. 237.
Anaphylaxis is mediated primarily by mast cells and perhaps basophils.
Chapter 14: Biology of Mast Cells and Their Mediators
Middleton’s Allergy Principles and Practice, 8th ed.
9. The percentage of which type of mast cell is increased in the skin of patients with atopic dermatitis? A. MCTC B. MCTCT C. MCT D. MCC
- C, MCT, p. 239
Healthy skin contains mast cells that are approximately 90% MCTC. The number of MCT is increased in the skin of patients with atopic dermatitis.
Chapter 14: Biology of Mast Cells and Their Mediators
Middleton’s Allergy Principles and Practice, 8th ed.
10. Aspirin-triggered asthma is associated with? A. Increased LTE4 in nasal secretions B. Increased LTE4 in urine C. Decreased PGD2 in urine D. Increased PGD2 in urine
- B, Increased LTE4 in the urine, p. 241.
Aspirin-triggered asthma is associated with increased LTC4 in the nasal secretions and increased LTE4 in the urine.
Chapter 14: Biology of Mast Cells and Their Mediators
Middleton’s Allergy Principles and Practice, 8th ed.
1. Where do the basophils develop? A. Bone marrow B. Fetal liver C. Liver D. Thymus
- A, Bone marrow, p. 252.
Like all granulocytes, basophils are of myeloid origin, developing from pluripotent stem cell precursors found in the bone marrow.
Chapter 15: Biology of Basophils
Middleton’s Allergy Principles and Practice, 8th ed
2. Which precursor cells differentiate into cells that morphologically and functionally resemble basophils? A. CD4+ B. CD8+ C. CD19+ D. CD34+
- D, CD34+, p. 252.
CD34+ precursor cells, when cultured in the presence of IL-3, differentiate into cells that morphologically and functionally resemble basophils.
Chapter 15: Biology of Basophils
Middleton’s Allergy Principles and Practice, 8th ed
3. Which of the following cytokines play a significant role in the survival and activation of mature basophils? A. IL-3 B. IL-4 C. IL-5 D. IL-13
- A, IL-3, p. 252.
IL-3 plays a significant role in the survival and activation of mature basophils. This is a
functional consequence of these cells’ retaining the expression of IL-3 receptors (CD123) at
remarkably high levels.
Chapter 15: Biology of Basophils
Middleton’s Allergy Principles and Practice, 8th ed
4. If there is an exposure to an allergen, the bone marrow activates and increases the production of the following cells: A. Basophils and eosinophils B. Basophils and mast cells C. B cells and eosinophils D. B cells and mast cells
- A, Basophils and eosinophils, p. 253.
The frequencies of these precursor cells are increased in asthmatics and in subjects who
have undergone experimental allergen provocation, suggesting a positive feedback
mechanism by which exposure to allergen results in bone marrow activation and increased
production of both basophils and eosinophils.
Chapter 15: Biology of Basophils
Middleton’s Allergy Principles and Practice, 8th ed
- Basophils have the ability to infiltrate into tissue sites. These “rolling” events are remediated through the expression of which of the following?
A. β1- and β2-integrin
B. β1-integrin very late antigen (VLA)-4
C. Intracellular adhesion molecules (ICAMs)
D. L-selectin (CD62L)
- D, L-selectin (CD62L), p. 253.
As with other leukocytes, the initial steps of basophil attachment to endothelium occurs during “rolling” events, in which selectins play a critical role. This is mediated through the expression of L-selectin (CD62L), which attaches to the ligands CD34 and MAdCAM-1.
Chapter 15: Biology of Basophils
Middleton’s Allergy Principles and Practice, 8th ed