Hypersensitivity Type 1 Flashcards

1
Q

What is the main immunoglobulin (antibody) involved in hypersensitivity type 1, describe its function

A

IgE

Involved in allergies and parasite infections

Triggers inflammation because it exists pre-bound to basophils and mast cells and cause them to degranulate when they bind to their antigen

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2
Q

Exaggerated hypersensitivity type 1 responses are the common cause of

A

Allergies

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3
Q

Why do hypersensitivity type 1 reactions occur

A

Some animals produce more IgE (genetics)

Some antigens naturally produce very strong IgE responses (wasp and bee stings)

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4
Q

Why are hypersensitivity type 1 reactions considered immediate

A

Because IgE is pre-bound to mast cells which creates a rapid response to allergens (minutes)

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5
Q

Mast cells (sentinel) use IgE as a detection mechanism, Give an example of when the IgE response is appropriate?

A

Internal parasitic worms activate mast cells

Mast cells release chitinase which destroy the parasite’s outer covering and attracts eosinophils to destroy them

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6
Q

Describe the mechanism of activation of mast cells/basophils/eosinophils due to IgE what are the signs of this occurring?

A

IgE is pre-bound to these cells, When it’s appropriate antigen binds to IgE, it causes the mast cell to

Degranulate

Release interlukin 31 which sensitizes and stimulates pruritis

Release histamine and heparin (vasodilation and increased capillary permeability)

Attracts eosinophils

Signs: redness, pale MM, swelling (local edema) and itchiness

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7
Q

What is Atopy

A

The genetic predisposition to allergic disease (type 1)

Affected animals often have increased production of IgE and become sensitized to allergens common to the environment

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8
Q

What breeds are more susceptible to allergic diseases, which ones are less susceptible?

A

More: terriers, Dalmatians, retrievers

Less: non pure bred dogs

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9
Q

Describe the 3 main causes of allergic skin disease (atopic dermatitis), give an example of each.

A

Contact with environmental allergen (skin keratin defect -people with allergy to metal)

Injected allergen (flea saliva, culicoides/midge bites in horses called Sweet Itch, mosquitoes)

Ingested allergen(food) (from the gut, a small amount of dietary protein is absorbed intact, may or may not have GI signs, absorbed allergen may travel through the blood and bind to skin mast cells)

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10
Q

What are the signs of allergic skin disease (atopic dermatitis)

A

Often first seen in younger adults

Characterized by pruritis (intense itching in the feet and ears is often the first sign)

Skin lesions/changes (hives/urticaria)

Erythema (red skin)

Scratching/licking feet or rubbing leads to damage to the skin (alopecia, thickening (hyperkeratosis) and pigmentation)

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11
Q

Describe hives/urticaria

A

Raised lumps

Small or large

Warm, edematous

Pruritic

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12
Q

How is allergic skin disease (atopic dermatitis) diagnosed

A

Exclusion in the diet or environment: best for diet allergies (cut out possibilities one by one before diagnosing an allergy) -time consuming

Skin testing: inject potential allergens into the skin and see if there is a reaction (patches) -best for environmental allergies

Serum testing: better at ruling things out

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13
Q

How do you treat allergic skin disease (atopic dermatitis)

A

Washing/bathing frequently especially for contact dermatitis. Use tepid/cool water and moisturizing shampoos (oatmeal is a good anti-pruritic)

Reduce inflammation with antihistamines, corticosteroids, atopica (cyclosporin), oclacitinin (apoquel), monoclonal antibody (reduces itching)

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14
Q

How do you prevent allergic skin disease (atopic dermatitis)

A

Remove the source of allergen (environmental changes, reduce flea infestation, stable horses to avoid midges, diet changes)

Dietary exclusion (feed a simple diet, novel proteins, test different proteins)

Changing to a less inflammatory diet (increase omega-3 fatty acids -fish/flax/canola)

Desensitization (allergy shots, aim is to switch Ig synthesis to IgG, gradually increase doses)

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15
Q

Why is evening primrose oils not helpful in allergic skin disease

A

Contains omega 6 fatty acids (not omega 3s)

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16
Q

What is similar about hay Fever and asthma, what is the difference between the two?

A

Hay fever (allergic rhinitis) and asthma are both IgE mediated hypersensitivities of the respiratory tract. The difference depends on where the antigen is trapped

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17
Q

Large particles get trapped in the upper airways and cause

A

Hay fever

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18
Q

Small particles are carried down into the lungs and cause

A

Asthma

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19
Q

True or false

Hay fever is mainly a people problem

A

True

20
Q

What are the signs of hay fever

A

Nose: sneezing, watery nasal discharge, blocked passages, itchy nose

Eyes: itchy, red, swollen, may feel gritty, blueness below skin (people)

Throat: soreness, itchy

Sleep: mouth breathing and fatigue

21
Q

Who is asthma seen in

A

Cats
Basenij dogs
People

22
Q

What are the signs of asthma

A

Wheezing
Dyspnea

Can be acute, severe and even fatal

23
Q

How is asthma diagnosed

A

Administrating a bronchodilator -if it works then bronchoconstriction is causing the problem

24
Q

Hay fever and asthma is less likely in humans if

A

You have lots of siblings and were raised on a farm

25
Q

Asthma and hay fever is more likely if

A

There is a family history

26
Q

What is an allergy often caused by if it is seasonal

A

Pollens from any type of plant or spores from fungi

27
Q

What are allergies usually from if they are year round

A
Dust mites
Roaches (produce allergen) 
Animal dander 
Fungi 
Molds
28
Q

Dander allergens are more of a concern working

A

Indoors

29
Q

True or false

Fine dander like on cats and rabbits are more likely to cause hay fever/asthma

A

True

30
Q

What is the main allergen found on cats

A

Salivary protein that sticks to hair when licking

31
Q

True or false

There is a diet that contains antibodies against common cat salivary allergens to help reduce reactions in people

A

True

32
Q

What is anaphylactic shock

A

An extreme, life threatening allergic reaction to an allergen

33
Q

Anaphylactic shock is a major concern when;

A

Giving a biological product (vaccine) due to injection of an actual antigen or live virus

Penicillin (common)

34
Q

How long does it take for an anaphylactic shock reaction to occur

A

15-30 minutes

35
Q

What should veterinary practices always have on hand to prepare for anaphylactic reactions

A

Epinephrine
Antihistamines
Corticosteroids

36
Q

Major signs of anaphylactic reactions are seen in the lungs and GI tract (shock organs) Whichever predominates depends on the species, describe when they are seen

A

Lungs AND GI: horses
Lungs only: cattle, sheep, cats
GI: dogs

37
Q

Anaphylactic reactions also may be seen in the skin, especially in

A

Cats

38
Q

Why are the kidneys and skeletal muscles not affected in anaphylaxis

A

Because mast cells are driving the anaphylactic response and these are mainly found at entry points of the body (GIT and lungs)

These areas have few sentinel cells

39
Q

What are some common respiratory signs of anaphylaxis

A

Increased RR
Dyspnea
Coughing

40
Q

What are some common GI signs of anaphylaxis

A

Vomiting (not in horses)

Increased defecation/diarrhea (may be bloody)

41
Q

What are some other signs of anaphylaxis

A

Skin irritation (cats) and scratching around the head

Weakness
Incoordination
Collapse
Death

42
Q

Antihistamines are used in treatment of anaphylaxis in

A

Antihistamines: diphenhydramine (benadryl)

Often given in 2.2mg/kg

Often used in early signs

43
Q

Why should you not give antihistamines in the food/orally

A

Takes longer to absorb

Patient may be vomiting or have diarrhea

44
Q

What does epinephrine do in the treatment of anaphylaxis

A

Stabilizes mast cells and stops degranulation

Reverses vasodilation

dilates smooth muscle to help breathing

Rapidly absorbed if given IM or SQ

Dose for cats and dogs is 0.1 to 0.5 ml or 1:1000 epinephrine solution

45
Q

IV fluids are given to help treat anaphylaxis to support circulation, what are some commonly used fluids

A

Corticosteroids
Prednisolon sodium succinate
Dexamethasone phosphate in water

46
Q

A patient came in and got a first time vaccine along with a Booster vaccine, he ended up having a severe allergic reaction and came back to the clinic. What is the most likely cause of the reaction, explain why

A

The booster vaccine (not the first time vaccine) because the immune system/body has been primed against the vaccine that was boosted at the first vaccination appointment so the reaction was ready the second time.

The first time vaccine would not have created a reaction so fast because the immune system has not be primed against it before