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Hypersensitivity reactions Flashcards

1
Q

Which type of bacteria are MAC (membrane associated attack complexes) most effective?

A

Gram NEGATIVE bacteria

Limited peptidoglycan to fight against

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2
Q

Which Ig doesn’t have a hinge region, making it harder for proteases to process the antibody

A

IgM

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3
Q

Which is better at activating complement/opsonization, IgG or IgM?

A

IgM

But IgG is smallest antibody, so can go through vessels into tissue easier!

Because IgM is so large, it rarely enters tissue

IgM can act as a BCR when bound to B cells

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4
Q

Type I hypersensitivity antibody type

A

IgE

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5
Q

Type I hypersensitivity’s other name

A

Immediate hypersensitivity

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6
Q

Type II hypersensitivity’s other name

A

Cytotoxic hypersensitivity

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7
Q

Type II hypersensitivity’s antibody type

A

IgG, IgM

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8
Q

Diseases associated with Type II hypersensitivity (6)

A

1) Drug reactions
2) Pemphigus
3) Pemphigoid
4) IMHA
5) Transfusion reaction
6) Cryoglobulinemia

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9
Q

T or F: Type II hypersensitivities need complement to work

A

False. Many mechanisms use complement, but not complement-dependent

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10
Q

Mechanism of Type II hypersensitivity (5)

A

Antibody binds autoantigen → +/- activate complement

1) Neutrophil cytotoxicity
*Complement binds Ig → chemotaxis for neutrophil → releases proteases/ROS →cell damage
*PF

2) Opsonization + Phagocytosis
*Complement binds Ig→ chemotaxis for macrophage → eat complement and bound Ig + cell
*IMHA

3) MAC formation

4) Apoptotic response
*Complement binds Ig → chemotaxis for NK cell → release perforin, granzymes that poke holes in cell PM →lysis

5) Disruption of cell function
*NO COMPLEMENT
*Ig binds autoantigen RECEPTOR → 2 options
A) Ab binds R; Noncompetitive inhibition for R
*Myasthenia gravis
B) Ab binds R; activates R without its normal signal
*Hyperthyroidism

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11
Q

Type III hypersensitivity antibody type

A

IgG, IgM

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12
Q

Type III hypersensitivity’s other name

A

Immune-Complex mediated hypersensitivity

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13
Q

Diseases from Type III hypersensitivity (4)

A

1) SLE
2) DLE
3) Purpura hemorrhagica
4) Vasculitis

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14
Q

Type IV hypersensitivity antibody type

A

None → cell mediated

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15
Q

Type IV hypersensitivity’s other name

A

Late phase, cell mediated hypersensitivity

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16
Q

4 types of Type IV hypersensitivity (A-D)

A

A) Th1 → macrophage activation → contact dermatitis
B) Th2 → eosinophil activation → chronic allergy/asthma
C) CD8 → Cytotoxic → Contact dermatitis, EM, SJS
D) T cell → neutrophil activation

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17
Q

True or False: Atopic dogs typically have less IgA

A

True. Theory that increased IgE may be compensatory for lack of IgA

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18
Q

Functions of basophils (3)

A

1) IgE-mediated anaphylaxis
2) IgG-mediated anaphylaxis via FcgR1
3) Release PAF, which is more effective than histamine at increasing vascular permeability

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19
Q

PAF relative to histamine

A

PAF is more effective than histamine at increasing vascular permeability

PAF made by neutrophils

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20
Q

What can trigger cutaneous basophil hypersensitivity

A

Ticks, fleas, insects

*Characterized by marked basophil infiltrate and fibrin deposition
*Mediated by T cells and IgE/IgG
*Pathogenesis of IBH

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21
Q

Type I hypersensitivity can result 3 major mast cell product families. What are they?

A

Antibody cross-links to FcER1-bound IgE →FcER1 with intracellular tyrosine kinase dimerize and produce (4):

1) Phospholipase A → arachidonic acid → prostaglandins and leukotrienes
2) Protein kinase → (phospholipase C) → intranuclear → gene transcription → Cytokines
3) Protein kinase → filament formation → Granule exocytosis

*Phospholipase A for Arachidonic (A)
*Phospholipase C for Cytokine (C)

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22
Q

What organs normally clear immune complexes

A

Spleen, liver

If not→ deposited in tissue

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23
Q

External antigens that can trigger immune complexes (5)

A

1) Drug
*Dobie + sulfa drug
2) Self antigens
3) Foreign serums
*Monoclonal antibodies
4) Bacteria
5) Diet hypersensitivity

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24
Q

2 major forms of Type III hypersensitivity

A

1) Local reaction → “Arthus reaction”
*Localized necrotic vasculitis

2) Generalized reaction → “Serum sickness”
*Complement gets stuck in small vessel → activates complement → recruits neutrophil → release protease + ROS → damage to endothelial cells + vessel BMZ → leaks to surrounding tissue

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25
Clinical signs of serum sickness (Type III hypersensitivity, generalized)
*Systemic inflammation *Splenomegaly *Urticaria *Fever *Arthralgia
26
Which cells are involved in Type IV hypersensitivity
T cells, NK cells
27
What type of hypersensitivity is allergic contact dermatitis
Type IV
28
What pathogens are type IV hypersensitivites designed for?
Intracellular pathogens *Mycobacteria *Fungi Also tumor immunity, transplant rejection
29
Why is type IV hypersensitivity DELAYED?
Requires recruitment of cells, which takes time
30
Mechanism of Type IV hypersensitivity?
Small molecule binds to self-cell → acts as a "hapten" to make "self" seem antigenic → APC presents haptenized self-antigen on MHC cl II → binds naive Th cell *If LC releases IL-12, induces Th1 immune response → IFNg →recruit macrophages →TNFa, IL-1 → ROS, lysozymes attack "self" *If LC releases IL-6 induces Th17 → activates neutrophils → ROS, proteases → tissue damage
31
Diseases of type IV hypersensitivity (9)
1) Contact dermatitis 2) FAD 3) Bacterial hypersensitivity 4) Food 5) Tick bite 6) SJS 7) EM 8) TEN 9) Drug hypersensitivities
32
What type of hypersensitivity reaction is Urticaria and Angioedema
Type I & Type III
33
Predisposing factor for urticaria/angioedema in dogs
Atopic dermatitis Autoantibodies to high affinity IgE receptors or IgE Variably pruritic
34
T or F: Horses usually get angioedema along with their urticaria
False If they are going to get angioedema, they usually also have urticaria (1st urticaria, then angioedema) Location of angioedema: muzzle, eyelid, ventrum, distal extremities
35
Horse breeds predisposed to urticardia
Arabian, Thoroughbred (also more predisposed to AD)
36
Locations of horse urticaria on body
Neck Trunk Proximal extremities
37
Drugs implicated in urticaria in horses
Penicillin Phenylbutazone
38
T or F: histamine levels correlate with cAD severity
FALSE
39
Which cytokines promote Th1 response
IL-12, IL-18 (Goal of immunotherapy is to convert from Th2 to Th1 or Treg)
40
For CAFR, what infectious agent can trigger a Th1 response in Peyer's patches → IGNg → suppress Treg → food allergy development
Reoviruses (intestinal infx) (shown for Th1 gluten intolerance in humans)
41
What percent of CAFR dogs have GI signs
10-30%
42
Major allergen for FAD
Cte f1
43
What type of hypersensitivity reaction is FAD
Initially local type IV (mononuclear) Over time, replaced with type I → eosinophils
44
What are causes for gyrate (polycyclic; bizarre shapes) urticaria in horses
*Drug reactions *EM (does not pit)
45
Causes of papular urticaria in horses
*Stinging insects *Folliculitis (esp if oozing, crusts, alopecia after)
46
Causes of giant urticaria in horses (up to 40 cm!)
Vasculitis
47
In dogs with cAD, are LC increased or decreased in epidermis
Increased
48
What are other risk factors for cAD?
* Month of birth → born during allergy season = ↑ risk * Maternal diet → fed non-commercial diet during lactation = ↓ risk * Use of probiotics → mixed results
49
Which cytokine suppresses contact hypersensitivity reactions (type IV)?
IL-10
50
Which plants can cause contact hypersensitivity (6 plants + 5 miscellaneous causes)
*Wandering Jew plant *Spiderwort * Spreading dayflower *Doveweed *Hippeastrum leaves and bulbs * Asian jasmine * Dandelion Misc: *Cedar wood *Carpet deoderizer *Cement *Feathers *Tobacco
51
Which medications can cause contact hypersensitivity (5)
1) Neomycin 2) Propylene glycol 3) Bacitracin 4) Tetracaine, other "caines" 5) Benzoyl peroxide
52
T or F: contact hypersensitivity is pruritic
True. Highly pruritic
53
What type of hypersensitivity reactions are drug reactions
Type I Type II Type III Type IV
54
What is the secretory component relative to IgA
Secretory component is a peptide --> binds IgA dimers to form secretory IgA (SIgA) --> protects IgA from digestion by intestinal proteases
55
Can IgA act as an opsonin
No
56
Can IgA induce agglutination of antigens
Yes. Adheres to microbes to prevent entrance to body surfaces
57
Which cell does IgD attach to
B cells Acts as BCR Rarely in blood stream NOT in rabbits or cats (yet) Destroyed with heat (like IgE)
58
What is the function of IgD
regulates B cell responses Activates basophils (IL-1, IL-4, B-cell activating factor production)
59
How many constant regions does IgG have compared to IgE in its heavy chain
IgG: 3 (has 1 in its light chain also) IgE: 4
60
Which Ig can fix complement
IgM IgG
61
Which Ig can cross the placenta
IgG only
62
What type of hypersensitivity reaction is mosquito bite hypersensitivity
Type I
63
Although MOST of the time, demodectic mange is cleared by the innate immune response w/o need for adaptive immunity, which type of hypersensitivity can occur 2' demodex
Type IV hypersensitivity -CD8+ T cells are rare, but present on histopath (mostly monocytes)
64
What type of hypersensitivity is an arachnid (and insect) hypersensitivity
Type I (anaphylaxis) Type III
65
While we dont KNOW that canine eosinophilic F&F is a hypersensitivity rxn, if it IS, which hypersensitivity would it be?
Type I hypersensitivity (eos)
66
What triggers canine eosinophilic F&F
Insect bites BUT usually, insect bites get better over time, but this dz smolders Nasal bridge = site most affected
67
What type of hypersensitivity reaction is Staphylococcal hypersensitivity?
Type I (eosinophil, immediate) Type III (immune complex, vasculitis, neutrophils) Type IV (delayed, cell mediated) Neutrophilic dermal vasculitis (type III)
68
Breed predisposition to Malassezia hypersensitivity
Dogs: *American Cocker Spaniel *Australian Silky Terrier *Basset Hound *Boxer *Dachshund *English Poodle *Setter *Shih Tzu *West Highland White Terrier Cats: *Devon Rex *Sphynx
69
Most common environmental fungal hypersensitivity
Alternaria
70
What type of hypersensitivity is fungal hypersensitivity
Type I
71
T or F: hypersensitivity to dermatophytes are reported
True Can have IgE to trichophyton
72
What type of hypersensitivity reaction is Purpura hemorrhagica
Type III- immune complexing
73
Organisms that can trigger Purpura Hemorrhagic (5)
*Staphylococcus equi (or its vaccine) *Corynebacterium pseudotuberculosis *Rhodococcus equi *Equine influenza virus *Equine herpes virus type I Occurs 2-4w post infection
74
Clinical signs of purpura hemorrhagica
Urticaria, SC edema, Hemorrhage on mucosa + SC. Vasculitis (febrile, depressed, anorexic).
75
Other than horses, what other animal gets Purpura hemorrhagica
Pigs
76
Anaphylotoxins Definition
Complement components: *Potent neutrophil chemoattractants. *Promote smooth muscle contraction *Increased vascular permeability
77
Anaphylotoxins, name 2
C3a, C5a
78
2 types of adverse drug reactions
*Type A: Dose-dependent *Type B: Dose-independent
79
What is a Type A adverse drug reaction
Dose dependent Exaggerated, but normal response to medication. Result is due to the drug itself. Common, predictable Can happen in any individual
80
What is a Type B drug reaction
Dose-independent Bizarre reaction to drug. Not related to dose, normal pharmacological action of drug These occur at therapeutic doses. Uncommon, unpredictable Often severe: high morbidity, mortality.
81
4 mechanisms for drug allergy
1) Hapten hypothesis 2) Danger theory 3) Pharmacological interaction concept 4) Viral reactivation
82
What is the Hapten Hypothesis, with regards to ADR
Hapten + Autologous protein (ie albumin, transferrin, integrins, selectins) = hapten-protein complex Hapten-protein complex = immunogenic. Initiate adaptive immune response
83
Example of a medication that is a hapten
Beta-lactam antibiotics (penicillin) Bind to albumin via lysine residues
84
Example of a medication that is a prohapten
Sulfamethoxazole. Metabolized by CYP2C6 to form sulfamethoxazole **hydroxylamine**. This can bind to autologous proteins w/cysteine residues --> antigenic PRO hapten means it needs to be PROCESSED to become a hapten.
85
What is the Danger Theory of ADR
*Danger signals (inflammation, oxidative stress, necrosis) trigger adaptive immune response *Danger signal can be induced by: -Drugs -Diseases treated by the drug This means the immune system is responding to the danger signal, rather than the foreignness of the drug itself
86
What is the pharmacological interaction concept of ADR
*Off-target binding of the drug to receptors on T cells --> T cell activation *Non-covalent binding with *TCR* or *MHC* on T cells *Immediate + independent of drug processing or metabolism
87
Which cells can be activated by haptens
B cells AND T cells
88
Which cells can be activated by pharmacological interaction concept
T cells ONLY
89
Drugs known to induce pharmacological interaction ADR
*Amoxicillin *Sulfamethoxazole *Ciprofloxacin *Iohexol *Lidocaine *Allopurinol
90
Diseases that are possibly a result of pharmcological interaction (ADR)
*Hepatotoxicity *SJS/TEN *MaculoPapular Exanthema (MPE) *Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)
91
What is Viral Reactivation of ADR
*Viral infections that INCREASE susceptibility to drug hypersensitivity (ie HIV, herpesvirus) *Selective expansion of viral-specific CD8 T cells that CROSS REACT with the drug
92
What is "Pseudo-allergy"
Non-immune-mediated activation of mast cells, eosinophils, basophils --> anaphylaxis *Off-target binding of drugs to MRGPRX2, C3a R, C5aR on these cells to activate *Do NOT use IgE or IgG Fc R
93
Drugs that cause Pseudo-allergy (AD)
*Opiods *NSAIDs *Radiocontrast *Vitamin K1 *Liposomal drugs
94
T or F: Mast cells need to be SENSITIZED to a drug prior to onset of a "pseudo-allergic" anaphylaxis
FALSE. Can occur IMMEDIATELY after drug exposure Do not need IgE, IgG4 to initiate this reaction. Use MRGPRX2 or anaphylotoxin receptors
95
Which receptor do opiods bind to on Mast Cells, which can initiate anaphylaxis?
MRGPRX2
96
Which medications can cause facial pruritus in cats?
*Methimazole *Spironolactone *Solensia
97
What type of hypersensitivity reaction causes pruritus
Types 1 and 4
98
What type of hypersensitivity reaction causes urticaria and angioedema
Type 1
99
Where is edema in the skin that causes urticaria
Dermis
100
Where is edema in the skin that causes angioedema
SQ
101
Drugs that cause a Type 1 Hypersensitivity reaction
*Penicillin *ampicillin *tetracycline *vitamin K *Amitraz *ivermectin, moxidectin *sulfonamides, *radiocontrast agents *chlorhexidine *HyLyt® shampoo *vaccinations
102
What type of hypersensitivity reaction is a pemphigus foliaceus-like ADR
Type 2. Antibodies bind to DSC1.
103
What is the difference between drug-induced and drug-triggered PF
Drug INDUCED: disease resolves once the drug is discontinued Drug TRIGGERED: disease continues despite d/c of drug
104
Which medications are associated with pemphigus foliaceus-like ADR
*Sulfonamides *Cephalexin *Oxacillin *Clavamox *Tetracycline *Promeris *Vectra 3D *Certifect *Nexgard *NSAIDs
105
What type of hypersensitivity reaction is vasculitis
Type 3- immune complexes
106
Which drugs have been associated with vasculitis
*Itraconazole *Meloxicam *Piroxicam *Sulfonamides *Human albumin
107
T or F: vasculitis is usually drug induced
False. Most often idiopathic
108
What are fixed drug eruptions
Delayed reactions to a drug that affect 1+ body region. Well circumscribed erythema --> edema --> bullae --> ulcerations. Scrotum commonly affected. Repeatable with re-exposure.
109
What type of hypersensitivity reactions are fixed drug eruptions
Type 4
110
What type of hypersensitivity reaction is EM, SJS, and TEN
Type 4
111
Amount of epidermal detachment for SJS vs TEN
SJS <10% TEN >30%
112
What type of hypersensitivity reaction is lupus erythematous-like ADR
Type 3 (+/- vasculitis)
113
What are systemic signs of a type 3 hypersensitivity reaction
*anemia *thrombocytopenia *polyarthropathy *protein-losing nephropathy.
114
What type of hypersensitivity reaction is Sweets Syndrome/ Neutrophilic dermatitis
Type 4
115
What medications are associated with Sweets syndrome
NSAIDs, antibiotics (metronidazole, beta-lactams), vaccinations
116
What type of hypersensitivity reaction is Superficial Suppurative Necrolytic Dermatitis (SSND)
Type IV. May be a CONTACT dermatitis
117
What breed develops Superficial Suppurative Necrolytic Dermatitis (SSND)
Miniature Schnauzers
118
What is the trigger for Superficial Suppurative Necrolytic Dermatitis (SSND)
Shampoos (natural OTC)
119
What is the difference between Superficial Suppurative Necrolytic Dermatitis (SSND) and Post-Grooming Furunculosis
Post-grooming furunculosis is infectious, SSND is sterile
120
Which non-skin clinical sign is common in CAEDE (Wells-like syndrome)
GI signs
121
Which non-skin clinical sign is common in Sweets like syndrome
IMPA, lameness
122
Which breeds are overrepresented for CAEDE
Mini schnauzer English bulldog
123
T or F: Drug allergy is dependent on the dose of the drug
FALSE. Its a Type B Adverse drug reaction (dose independent)
124
What body region is usually associated with allergic contact dermatitis
Sparsely haired regions (contact!) *Ventrum *Face *Ears *Scrotum *Perineum *Ventral paws
125
What is the different between allergic contact dermatitis (ACD) and irritant contact dermatitis (ICD)
ICD is a nonspecific reaction to an irritating, caustace substance. NO PRIOR EXPOSURE NEEDED. More directly cytotoxic to keratinocytes. ACD requires prior exposure/ sensitization (type 4 hypersensitivity, with possible type 1 component?)
126
Cause of SJS/TEN
Drugs EM is NOT usually drug induced
127
Pathomechanism for EM, SJS, TEN
Cytotoxic response by CD8 T cells and NK cells against keratinocytes *Keratinocytes are primed for targetting by infectious agents or drugs. *Apoptosis via: 1) EM: direct cellular cytotoxicity 2) SJS/TEN: soluble mediators of cell death Soluble mediators include Fas ligand, granzymes, perforin and, most importantly, **granulysin**
128
What is the possible animal equivalent to human EM (herpesviral
Feline herpes-associated EM
129
Soluble mediators of cell death in SJS/TEN
**Granulysin** Also: *Fas ligand *Granzymes *Perforin
130
Etiology of EM in animals
Idiopathic
131
Which type of hypersensitivity reaction often forms a vesicular rash?
Type IV hypersensitivity **CD8+ T cells kill the haptenized cells --> necrosis --> vesicles

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