Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Path - Immunology > Allergy > Flashcards

Allergy Flashcards

1
Q

What is an allergic disorder?

A

Immunological process resulting in immediate and reproducible symptoms after antigen exposure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is an allergen?

A

A harmless substance that triggers an IgE mediated immune response and causes clinical symptoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is sensitisation?

A

Detection of specific IgE by testing (skin prick/in vitro blood test)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does sensitisation show?

A

RISK of allergic disease
does NOT define allergic disease
So NECESSARY but NOT sufficient to cause allergy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What do allergens/venoms/helminths activate?

A

Cytokines:

  • IL-1alpha
  • IL25
  • IL33
  • TSLP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What do allergen cytokines activate?

A

Th2 cells (MAINLY)
Th9
ILC2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the Th2 effector cytokines?

What do they activate?

A

IL4
IL5
IL9
IL13

They activate eosinophils and basophils

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Explain the tfh2 cell pathway

A

allergen > signalling cytokines > Tfh2 > IL4, IL21 > B cells >IgE, IgG4 > IgE cross links mast cell > histamine, leukotriene, prostaglandin release

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What do histamines, leukotrienes, prostaglandins act ion?

A

Endothelium > increase permeability
Smooth muscles > smooth muscle contraction
Neurons>itching

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a risk factor for IgE antibody development / sensitisation ?

A

Skin defect e.g. atopic dermatitis
as it allows allergen entry
Skin dendritic. cells promote Th2 cytokine secretion much more efficiently than other dendritic subtypes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What kind of exposure induces immune tolerance?

A

oral exposure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does oral/Gi exposure promote immune tolerance?

A

Because Tregs from the GI mucosa inhibits IgE synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the function of eosinophil?

A

Host defence against parasites, bacteria, viruses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the key cytokine for eosinophil development and expansion?

A

IL-5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is normal IgE function?

A

To protect against helminth and parasitic infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is an unwanted effect of IgE function?

A

mast and basophil degranulation, associated to immediate hypersensitivity reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the 2 subtypes of mass cells in humans?

A

MC tryptase T in skin

MC chemotryptase CT in airway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is mast cell degranulation triggered by?

A

IgE/IgG receptors

G protein coupled receptors

19
Q

Explain mast cell/basophil degranulation

A

Cross linking of bound IgE > histamine, leukotriene, prostaglandin release

mast cell degranulation leads to:

  • recruitment of soluble proteins and inflammatory cells to site of infection
  • increase in rate of lymphatic flow back to regional lymph nodes
  • smooth muscle contraction in lungs, gut
20
Q

Factors that promote IgE production

A

Antigen dose
length of exposure
physical properties of antigen (source, water solubility, carbohydrates, resistance to heat/digestive enzymes)
route of exposure

21
Q

What is the order of age of onset for allergic diseases?

A

Infants: atopic dermatitis, food allerggy
Childhood: asthma, allergic rhinitis
Adults: drug allergy, bee allergy

22
Q

what are the theories for increased prevalence of allergic disorders?

A 
Hygiene hypothesis 
Increased childhood vaccination, exposure to antibiotics, 
lack of vitamin D in infancy 
Dietary factors 
Alteration in intestinal microbiome 
High concentration of dietary sugars
23
Q

What are clinical features of IgE mediated response?

A

MIN 2 ORGANS INVOLVED
SYMPTOMS MUST BE REPRODUCIBLE
SKIN: angioedema, urticaria flushing, itching
RESP: cough, SOB, nasal congestion, wheeze, red watery eye
GI: nausea, diahrroea, vomiting, hypotension

24
Q

What is evidence that the microbiomial environment can protect against asthma?

A

Amish vs Hutterite communities

Amish have lower asthma prevalence as there is higher LPS prevalence in dust samples in Amish homes

25
Q

What co-factors can trigger allergic symptoms?

A

Exercise
Alcohol
NSAID
Viral infection

26
Q

What allergen specific IgE (sensitisation) tests can you do?

A

Skin prick test (SPT)
Intradermal test
IgE blood test

27
Q

What does a skin prick test do?

A

Exposes pt to allergen extract solution through skin prick on arm
Looks for cross linking of IgE on skin mast cells > degranulation > release of histamine and other inflammatory mediators

28
Q

What controls do you use for a skin prick test?

A 
POSITIVE control (histamine) 
NEGATIVE control (dilutent)
29
Q

How do you identify a positive result in a skin prick test?

A

wheal >3mm greater than positive control

30
Q

What should you discontinue before SPT?

A

antihistamines /antidepressants containing antihistamine

for 48h prior

31
Q

how do intradermal test work?

A

same principle as skinprick

allergen is now injected into intradermal layer

32
Q

When are intradermal tests indicated?

A

To follow up negative venom or drug allergy test

If SPT is negative but story is convincing

33
Q

What is the benefit of SPT?

A

Excellent negative predictive value (no false neg)

34
Q

What is the benefit of intradermal test?

A

Excellent positive predictive value (no false positive)

35
Q

What are indications for IgE blood test?

A 
No access to SPT/IDT 
Patient can't stop antihistamine 
Patient has dermatographism (skin can't be scratched)
Patient has excessive eczema 
Hx of anaphylaxis 
Borderline SPT results
36
Q

What is increased serum tryptase a marker for?

A

systemic degranulation of mast cells during anaphylaxis

37
Q

When is it good to get a serum tryptase?

A

if anaphylaxis dx is uncertain e.g. during anasthesia pt becomes hypotensive with rash

38
Q

What is a food allergy?

A

An adverse health effect arising from specific immune response that occurs reproducibly on exposure to a given food

39
Q

What is a food intolerance?

A

non-immune reaction that includes metabolic, pharmacological, unknown mechanism

40
Q

What is an important risk factor for food allergy in children?

A

Atopic dermatitis

41
Q

Which investigation is best to CONFIRM anaphylaxis is occurring

A

Tryptase

42
Q

how do tryptase levels in anaphylaxis change over time

A

peaks at 1-2h

back to baseline in 6-12h

43
Q

what are allergy tests you can do as elective?

A 
SKin prick 
Intradermal 
Allergen specific IgE 
Basophil activation test 
Challenge test
44
Q

What are allergy tests you should do during acute episode?

A

Mast cell tryptase
Blood/urine histamine

– looks for evidence of mast cell degranulation –

Path - Immunology (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions