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PHA 223 > allergy > Flashcards

allergy Flashcards

1
Q

how many types of hypersensitivity reactions are there?

A

there are 4 types of hypersensitivity reactions. they are broadly classified based on cells and immune effectors that are involved

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2
Q

what type of hypersensitivity reaction is an allergic response?

A

an allergic response is a type 1 hypersensitivity reaction - as it was discovered first

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3
Q

what is an atopic allergy?

A

in Greek means out of place work.. it is an inappropriate reaction that is out of place

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4
Q

what are the two key players in atopic allergy’s?

A

1- mast cell( part of anatamine system abd found in mucosal tissues, gut, skin )
2- IGE-( particular antibody/ antiglobulin)

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5
Q

what happens when mast cells are released and dispersed within an extracellular environment?

A

mast cells undergo degranulation

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6
Q

are mast cells antigen specific?

A

no they are not antigen specific, they are part of the innate immune system. they have a FC receptor which it binds to. this allows it to target

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7
Q

what antibody is dominant in an allergic reaction?

A

IGE

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8
Q

when is IGE produced?

A

IGE is inappropriately produced in response to innocuous allergens that can medicate allergic reactions

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9
Q

are total IGE levels predictive of atopic disease?

A

no

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10
Q

what is an allergen?

A

an allergen is what drives an allergic response. they tend to be protein-based. they are low molecular weight, highly soluble and stable

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11
Q

why do we have allergens?

A

they are due to an inappropriate breakdown of tolerance

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12
Q

what is sensitisation?

A

it is the initial exposure to antigen leading to antibody IGE production

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13
Q

what happens in sensitization and where does it take place?

A

it is the differentiation of native T cells in the th2 phenotype cells. it takes place in lymph nodes. dendric cells have matured and carried allergens to lymph nodes. during expansion the cutokine environment switches to the th2 phenotype. and one of the key cytokines that mediate is IN4. this causes skweing

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14
Q

what is sensitization linked to?

A

it is thought to be linked to the allergen dose / intrinsic properties of allergen and the route of exposure.

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15
Q

what does sensitisation stimulation B cells do?

A

produce cytokines of immune response which provide more IL4 to initiate a class switch to producing IGE.

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16
Q

what is the consequence of an allergen response?

A

allergen passes through mucosa and is captured.
it is transported to lymph cells- prime to th2 phenotype.
skewes b cells to IGE phenotype- they then differenciate into plasma cells
these antibodies travel through body back onto the mucosa on mast cells using FC receotirs.
so if encountered again this causes corss linking- degranulation and signalling

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17
Q

what happens in an acute/ immediate response?

A

occurs in a range of tissues- vasoactive amines within the cell cause:
smooth muscle constriction
blood vessel constriction
increase in mucous production
never endings -pain and distress
and recruitment of other cells such as eonysophyls

18
Q

what happens in the scamatic?

A

Mast cellls binds to IGE receptors
these allergies lead to a signal in these cells.
consequence depends on allergen present

19
Q

what are the responses seen in an allergic response?

A

GI- diarrhoea/ peristalysis
eye/ nasal- wheeze or cough
blood- risk of anaphlactic shock- critical drop in BP and decreased in permeability

20
Q

what happens in the early stage of an allergic reaction?

A

physiological mechanism

kiss of organ function due to- mucous production/ vasodilation and swelling/ bronchoconstriction

21
Q

what happens in late stage of an allergic reaction?

A

we get WBC flodding into environment/ scarring

immunological mechanisms/ digestion of tissue smooth muscle.

22
Q

what are contained in mast cells and what are they used for?

A

histamine
leukotrines- effects vascular permeability
neutrophils and eosinophil attracting chemokines- this leads to WBC into tissue inflamatory cascade

23
Q

what are present in eosiniphils?

A

typcially found in the blood
recruited by macrunophil degranulation
conatin matalloproteinases an d collagenases- digestion of tissue
fibrotic cytokines- secrete due to fibrosis and scarring
t and b cells attracting chemokines- worsen effects

24
Q

what is seen in a lung and skin graph to show function?

A

both have an initial drop in function but later on a broader dip that lasts longer

25
Q

is allergic reaction a vigerous circle?

A

yes

26
Q

how much of the uk have an alergy?

A

1/3

27
Q

how much is spent each year on allergy medication?

A

aprox 1 billion

28
Q

what is an atopic disease?

A

often present with food allergies in children but can disappear overtime

29
Q

what allergy may develop at adulthood?

A

asthma

30
Q

are all allergic reactions presentation the same?

A

no but the response is

31
Q

IV allergens can result in what?

A

anaphylactic shock

32
Q

what is the pathway for an allergic reaction?

A

allergen to IGE> Granulation> amine and physiological reaction

33
Q

describe athsma reaction?

A
  • Chronic disorder of airways with variable airlow limitation
  • Recurrent epsoides of wheeze, breathlessness, chest tightness and cough( particularly at night)
  • Inhaled allergens most common ( although can be triggered by food and drugs)
34
Q

describe rhinitis

A
  • Most prevalent respiratory disease
  • Nasal itching, blockage, rhinorrea, anosmia( loss of smell and sense of taste) and frequent sneezing
  • Often linked with asthma and vice versa
35
Q

describe uricicaria and angiodema

A

URTICARIA- upper latyers of skin AND ANTGIODEMA- deeper layers of dermis

  • Raised itchy nettle rash also known as hives
  • Usually triggered by food and drug allergens
36
Q

describe eczema

A
  • Local erythematous inflammation of the skin

- Often appears In early childhood induced by food such as eggs and milk

37
Q

describe anaphylaxis

A
  • Most severe allergic reaction
  • Involves more than one body system- respiratory/ blood/ cardiovascular/ gi
  • Life threatening and can result in death without AD- epipinephrine( epipin)
  • Triggered by many allergens including foods/ deugs/ venoms and latex
38
Q

is there a link between genetics and allergies?

A

yes strong link

39
Q

what is the hygiene hypothesis?

A
  • developed world less causes
    -elstest child more likely to develop
    c-section- more likely to develop allergy
40
Q

how do you diagnose an allergy?

A

clinical history
skin prick test
challenge test

41
Q

what is a skin prick test?

A

allergen apploed to skin. reaction if granulation and swelling.

42
Q

what is a challenge test?

A
  • Can provoke an immune response by oral/ inhaled/ injected or skin contact to suspected allergens

PHA 223 (42 decks)

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