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Immunology > Exam 2- Type I Hypersensitivity > Flashcards

Exam 2- Type I Hypersensitivity Flashcards

1
Q

what is an inflammatory response that causes extensive damage to the host’s tissues, even death, called?

A

hypersensitivity or allergy

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2
Q

IgE-mediated type I hypersensitivity (immediate hypersensitivity) is caused by coming into contact with an antigen against which the host has ________________________

A

pre-existing IgE antibodies

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3
Q

where are high affinity Fc-epsilon-RI receptors found?

A

mast cells, basophils, and eosinophils

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4
Q

true/false: allergens are typically presented to the immune system as high doses

A

false: very low doses

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5
Q

which Th cell response is required to induce type I hypersensitivity reactions?

A

Th2

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6
Q

what do mast cell granules do?

A

potent mediators immediate hypersensitivity reactions

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7
Q

how are mast cells, basophils, and eosinophils activated once the IgE molecule is bound?

A

cross-linking of the Fc-epsilon-RI receptors

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8
Q

what are the primary and secondary mediators?

A

primary: pre-formed and stored in granules, immediate hypersensitivity
secondary: synthesized after or released by enzymatic breakdown of cell membrane phospholipids during degranulation process

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9
Q

is histamine short-lived or long-lived?

A

short-lived

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10
Q

is the genetic predisposition to develop Type I hypersensitivity multigenic?

A

yes

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11
Q

true/false: the majority of IgE in the body is present in blood

A

false

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12
Q

true/false: mast cells of non-allergic individuals have IgE antibodies bound to the surface of their mast cells

A

true

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13
Q

what are the phases of type I hypersensitivity?

A

sensitization phase
activation phase
effector phase

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14
Q

what does the “wheal and flare reaction” show?

A

locally dilated blood vessels engorged with red blood cells

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15
Q

what does the late phase reaction of type I hypersensitivity consist of?

A

accumulation of inflammatory leukocytes

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16
Q

what inhibits the late phase of type I hypersensitivity reactions (rich in eosinophils)?

A

corticosteroids, not antihistamines

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17
Q

what is allergic rhinitis?

A

airborne antigens react with IgE-sensitized mast cells in nasal passages and conjunctiva

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18
Q

what is system anaphylaxis or anaphylactic shock caused by?

A

systemic release vasoactive mediators (mainly histamine and leukotrienes)

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19
Q

what are the two antibody based tests for diagnosis of allergies?

A

radioallergosorbent test (RAST)
ELISA

20
Q

what classes of drugs are given for therapy for allergies?

A

antihistamines
antileukotrienes
corticosteroids
epinephrine
cytopoint

21
Q

how does allergen immunotherapy work?

A

shift towards allergen-specific IgG production
shift to Treg subset which suppressed Th2 response

22
Q

what is the principle protective function of IgE-mediated immune reactions?

A

readication of parasitic worms such as helminths

23
Q

what do eosinophils release in response to their Fc-epsilon-RI receptors binding to IgE and cross-linking?

A

major basic protein (MBP)

24
Q

true/false: allergy shots lead to induced Treg response against the allergen used in the shots

A

true

25
Q

where is most of the IgE in the body?

A

bound to Fc receptor Fc-epsilon-RI on mast cells, basophils, and eosinophils

26
Q

what is the sequence of events for immediate hypersensitivity?

A

antigen exposure
activation Th2 cells for the antigen
cytokine help from Th2 cells to B cells
class switching to IgE
production IgE
IgE binds to Fc receptors on mast cells
re-exposure of antigen

27
Q

what does it mean that allergens are multivalent?

A

have one or more epitopes that are repetitive, and IgE response mounted against those epitopes

28
Q

what cytokines do Th2 cells produce?

A

IL-4, IL-5, IL-13

29
Q

what does the cytokine IL-4 do?

A

helps allergen-specific B cells class-switch to IgE

30
Q

what does the cytokine IL-5 do?

A

activates eosinophils- common in many immediate hypersensitivity reactions

31
Q

what does the cytokine IL-13 do?

A

stimulates epithelial cells to secrete increased amounts of mucus

32
Q

what cytokine is significantly higher in severely allergic individuals?

A

IL-4

33
Q

how are mast cells and basophils activated by IgE?

A

cross-linking of the Fc-epsilon-RI receptors

34
Q

what is the difference between primary and secondary mediators in hypersensitivity reactions?

A

primary: pre-made and released immediately: immediate hypersensitivity
secondary: synthesized or released by enzymatic breakdown of cell membrane phospholipids during degranulation process

35
Q

are histamine’s actions short-lived or long-lived?

A

short-lived because it is rapidly catabolized

36
Q

what are the actions of histamine?

A

leakage plasma into tissues
vasodilation
increased peristalsis and bronchospasms

37
Q

what are the actions of prostaglandins?

A

vasodilation
bronchoconstriction

38
Q

is histamine stronger acting than leukotrienes?

A

no, leukotrienes are much stronger and longer lasting
more potent bronchoconstrictors and stimulators of vascular permeability and mucus secretion

39
Q

what are important cytokines that mast cells produce in hypersensitivity?

A

TNF-alpha: inflammation
IL-4: Th2 response

40
Q

what causes the late phase reaction after the wheal and flare reaction (2-6 hours)?

A

accumulation inflammatory leukocytes: neutrophils, eosinophils, basophils, and CD4+ Th2 cells

41
Q

true/false: the late phase reaction is rich in eosinophils

A

true

42
Q

chronic inflammation in asthma is associated with increased presence of ___________, ___________, ___________, and _____________

A

lymphocytes
eosinophils
neutrophils
other leukocytes

43
Q

what is the difference in food allergies and food intolerances in presenting signs?

A

food allergies: itching and skin problems
food intolerances: diarrhea or vomiting

44
Q

what is in the cutaneous inflammatory infiltrate in dermatitis?

A

mast cells
dendritic cells
low numbers eosinophils and neutrophils

45
Q

what are the main vasoactive mediators released in systemic anaphylaxis?

A

histamine and leukotrienes

46
Q

what are the two antibody based tests for diagnosis of type I hypersensitivity?

A

radioallergosorbent test
ELISA

Immunology (21 decks)

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