Hypersensitivity Flashcards
Allergy
Hypersensitivity reaction to an antigen
Allergen
allergen that leads to allergic reaction
Sensitization
exposure to antigen or allergen
Type 1 sensitivity
Immediate
Type 2 sensitivity
anitbody-mediated cytotoxic hypersensitivity
Type 3 sensitivity
immune complex
Type 4 sensitivity
delayed-type hypersensitivity
how soon until type 1 hypersensitivity
within minutes of exposure
Characteristics of type 1 hypersensitivity
Anaphylaxis
Common allergy
Skin, respiratory tract, gut
What Ig is responsible for type 1 reactions
IgE
What IL are responsible for type 1 reaction
IL-4,
IL-5
What happens during acute type 1 reaction
IgE binding in high affinity reactions
Mast cells, basophiles, and neutrophils
What happens during chronic type 1 reaction
IgE binding on Dendritic cells and monocytes
What are some type 1 effector cells
Mast Cell
Basophil
Eosinophil: piece meal destruction substances
What do mast cells do as Type 1 effector cells and what are the 2 phases
Acute phase: severe local reaction
Late phase: edema, redness, pruritus
What are three main types of allergies in domestic animals
Atopic dermatitis
food allergy
Allergic inhalant dermatitis
How are skin allegories diagnosed
Wheal flare reaction in 10-20 minutes followed by late phage 6-12 hours
Antigens injected into dermis
Characteristics of desensitization therapy to allergies
High or low dose
Promote production of IgG rather than IgE
Want to switch immune response from Th2 to Th1
What are some characteristics of vasogenic shock
rapid smooth muscle contraction in bronchi, gas. tract, uterus, and bladder
Severe vascular pooling due to peripheral vasodilation
Where does ruminant have anaphylaxis
Lung
Where does horse have anaphylaxis
Respiratory tract, intestine
Where does swine have anaphylaxis
Respiratory tract, intestine
Where do dogs have anaphylaxis
Hepatic vein constriction
Where do cats have anaphylaxis
respiratory tract, intestines
What are characteristics of type 2 sensitivity
rapid destruction of foreign red cells bound by antibody
reaction to ones own cells
What does type 2 reaction release
complement fragments
degranulation of mast cells
cytokines
What is the main similarity between type 1,2,&3 sensitivities
Antibody mediated
What are examples of type 2 reactions
Transfusion reactions
-neonatal isoerythrolysis
Cross-match between donor and recipient
-essential in pig, horse, dogs, and cats for first transfusion
Where do type 3 reactions occur
Kidney
Eye
Joint
What are characteristics of type 3 sensitivity
IgG
Immune complexes occur
activation of complement
What are the three significant pathways of type 3 reactions
- Cytokines IL-1 and TNF-a cause local tissue damage
- Immune complexes form, phagocytes activated, neutrophils degranulate
- Immune complexes activate complement
Arthus reaction is
Local tissue reaction
Generalized immune complexes
circulating complexes
serum sickness
Organ damage
What is serum sickness
Generalized vasculitis
neutropenia
Membranoproliferative glomerulonephritis….
IC deposits in the glomerulus Proteins leaks into the urine loss of oncotic pressure Small molecules such as anti-thrombin 3 lost heartworm
What’s type 4 sensitivity
cell mediated immune response
T helper 1 cytokines gone wrong
Recruit more T cells and macrophages= more chemokines= more cells
What is the most important cytokine in type 4 hypersensitivity
IFN-gamma
Type 4 pathophysiology
Type 1 cytokines fail to kill microorganisms
tubercles form: multinucleated giant cells
mycobacterium bacilli
most common is chemicals and large particles
Allergic contact dermatitis
Type 4 sensitivity in dermis
poison ivy
Hypersensitivity
Inappropriately vigorous immune response to foreign antigen
