Chapter 16 Flashcards
Allergy is also known as _______________
Hypersensitivity
Define hypersensitivity.
The condition of altered reactivity or exaggerated immune response to allergens (Ag) that is manifested by inflammation.
Two types of allergens
exogenous and endogenous
Which type of allergens originate outside the host?
exogenous
Which types of allergens involve the host’s own tissue?
endogenous
immediate allergies are (exogenous or endogenous)
exogenous
IgE mediated (exo or endo)
exogenous
Involves mast cells and basophils (exo or endo)
exogenous
Anaphylaxis and atopic allergies such as hay fever and asthma (exo or endo)
exogenous
Exogenous allergens, those that originate outiside the host, are described by:
- immediate allergy
- IgE mediated
- involves mast cells and basophils
- anaphylaxis and atopic allergies such as hay fever and asthma
Endogenous allergens, those that involve the host’s own tissue, are described by:
- autoimmune diseases
- systemic lupus erythematosus
- blood incompatibilities
- graft rejections
Autoimmue diseases (exo or endo)
endogenous
Systemic lupus erythematosus (exo or endo)
endogenous
Blood incompatibilities (exo or endo)
endogenous
Graft rejections (exo or endo)
endogenous
Categories of hypersensitivity reactions
Type I, II, III, and IV
atopy is defined as:
a chronic local allergy such as hay fever or asthma
anaphylaxis is:
a systemic, fatal allergic response that blocks airway obstruction and produces circulatory collapse
Type I hypersensitivity
atopy and anaphylaxis
Type II hypersensitivity
cytotoxic response
transfused blood mismatches to the recipient’s blood type
Type III hypersensitivity
Immune complex reactions
systemic lupus, multiple sclerosis
Type IV hypersensitivity
delayed hypersensitivity reactions
occur hours or days after the antigenic challenge
graft rejection
If a hypersensitivity reaction occurs hours or days after the antigenic challenge, what type is it?
Type IV
What type of hypersensitivity includes graft rejection?
Type IV
Immune complex reactions are included in which type ?
Type III
Systemic lupus or multiple sclerosis are in which catergory of hypersensitivity?
Type III
If a patient has a cytotoxic response what category of hypersensitivity is it?
Type II
Transfused blood mismatches the recipient’s blood type causing a cytotoxic response…Name the category.
Type II
Hay fever is type …
Type I
Asthma is in type…
Type I
Atopy and anaphylaxis are part of which catergory?
Type I
Predisposition for allergies is inherited for which category?
Type I
Other than predisposition what else can trigger Type I allergic responses?
age, geographic locale, and infection
How is the Type I allergic response triggered?
A first dose of the allergen is sensed by the body that sets it up for when a second dose is introduced that activates the response.
Participants of Type I allergic response are:
IgE
basophils
mast cells
agents of inflammatory response
Type I allergens include:
- inhalants
- ingestants
- injectants
- contactants
How are allergies diagnosed? (type I)
Allergies are diagnosed with in vitro and in vivo tests that assay specific cells, IgE, and local reactions.
Describe the physiological steps of IgE mediated allergies.
When the allergen is initially introduced to the system it goes into the tissue fluids and lymphatics.
The lymphatics take the allergen to the lymph nodes it’s recognized by the specific clones of B-cells.
This activates the B-cells and they proliferate into plasma cells.
The plasma cells make reagin IgE.
IgE has a Fc receptor region with an affinity for mast cells (located in tissues only) and basophils.
When IgE binds to the mast cells and basophils in the tissues it triggers reactions to the allergen.
Mast cells and basophils are found in —-
connective tissues of all organs.
There is a higher concentration of mast cells and basophils in which 4 parts of the body?
lungs, skin, GI tract, and GUT
Basophils circulate in the _______ but migrate readily to the _______.
blood, tissue
Both basophils and mast cells can bind _____ during _________.
IgE, sensitization
Each basophil and mast cell carries how many cell receptors?
3 x 10^4 – 1 x 10^5
The cell receptors of basophils and mast cells can attract how many IgE molecules?
1 x 10^4 – 4 x 10^4
Basophils and mast cells produce ______________ that act as ____________.
cytoplasmic granules, chemical mediators
How many cytoplasmic granules (chemical mediators) do mast cells and basophils produce?
24
Name 5 of the cytoplasmic granules (chemical mediators) produced by basophils and mast cells.
- histamine
- serotonin
- badykinin
- prostaglandin
- leukotriene
What are the 3 actions of the chemical mediators (cytoplasmic granules) produced by basophils and mast cells?
- smooth muscles
- dilate blood vessels
- constrict bronchioles
When are the granules released into the tissues?
There is a tendency to degranulate when properly stimulated by an allergen.
IgE mediated allergies are part of which category of allergic response?
Type I
Mast cells and basophils are involved in which category of allergic response
Type I
Name 4 atopic (type I) diseases.
- asthma
- dermatitis
- food allergy
- drug allergy
Define asthma.
Respiratory disease characterized by episodes of impaired breathing due to severe bronchoconstriction.
How many people suffer from asthma in the US?
10 million
Define dermatitis.
Intensely itchy inflammatory condition of the skin (eczema)
Eczema is known as
“the itch that rashes”
Define food allergy.
Compounds that are allergens either from food digestion or from additives such as preservatives or flavoring.
Define drug allergy
Compounds that stimulate allergic reactions.
Allergy is the most common side effect of treatment.
Any tissue can be affected.
Which is the number one drug that causes allergic reactions?
penicillin
Name 5 types of drugs people are allergic to.
penicillin synthetic antimicrobics (sulfa drugs) aspirin opiates anesthetics
Anaphylactic shock is what type of allergy?
Type I
What is cutaneous anaphylaxis?
The wheal and flare inflammatory reaction to the local injection of an allergen
Describe systemic anaphylaxis?
Sudden respiratory and circulatory disruption that can be fatal in a few minutes.
Systemic anaphylaxis is usually caused by _______ and _______.
antibiotics and sera
Anaphylaxis is also caused by _______.
Bee stings. Bee venom contains complex allergens and enzymes creating long-lasting sensitivity (up to several decades)
The concentration of mediators and the strength of responses is ______ and ______ in anaphylaxis as compared to atopy.
greater and wider amplified
How quickly can anaphylaxis kill a person?
within 15 mins
For what reason does anaphylaxis work so quickly?
there is a massive outpouring of mediators into the tissues and blood. These act rapidly on the target organs.
How are allergies (type I) treated?
Allergies are treated with antihistamines that interrupt the allergic response at certain points
Name 2 antihistamines
Terfenadine (Seldane)
Epinephrine (adrenaline)
Allergic reactions can be prevented by…
desensitization therapy (hyposensitization)
About 70% of allergic patients can benefit from ___________ of specific allergens as determined by skin tests.
controlled injections
Reactions that Lyse Foreign Cells are part of which type?
Type II
Reactions that cause foreign cells to lyse….
this disease is a complex group of syndromes that involves complement - assisted destruction (lysis) of cells and IgG and IgM Antibodies
What type of antibodies are lysed in Type II reactions?
IgG and IgM antibodies
Type II reactions include ____ reactions and some types of ________
transfusion, auto immunities
The target cells in Type II lysing are _______
Red blood cells but others can be involved
The ABO isoantigen markers on red blood cells are determined __________ and are comprised of __________.
genetically, glycoproteins
How many ABO antigens do we inherit.
2 - one from each parent
How many alternatives are there for ABO antigens?
3 - A B and O
____ and ____ alleles are dominant over ____.
A and B — O
Which 2 alleles are codominant with each other?
A and B
What are the genotype possibilities for Type A blood?
AA or AO
Genotypes for type B blood
BB or BO
Genotypes for AB blood
AB
Genotype for type O blood
OO
What is the molecular basis for type A blood?
Type A has an enzyme that adds N-acetyl-galactosamine to the receptor of the WBC.
What is the molecular basis for type B blood?
Type B has an enzyme that adds D-galactose
What is the molecular basis for type AB blood.
Type AB has both carbohydrates.
D-galactose
N-acetyl-galactosamine
What is the molecular basis for type O blood?
Type O lacks the enzymes and genes to add a terminal carbohydrate molecule to its RBC receptors.
At early infancy we are exposed to _________ that mimic the structure of ___________. This causes us to become sensitized and produce __________.
surface molecules of bacteria
A and B isoantigens
corresponding antibodies
How do humans develop Antibodies against Rh factors?
Through placental sensitization (mother Rh- and unborn child is Rh+) or transfusion but not through exposure to microbes.
Immune complex reactions are part of which category of hypersensitivities?
Type III
Describe immune complex reactions
Immune complex reactions involve the reaction of soluble allergens with antibodies and depositing the resulting mixture (complex) in basements of membranes of epithelial tissue
Immune complex reactions (type III) produce ____ and ____ after repeated exposure to ______ and the activation of _______
IgG and IgM
allergen
complement
In type II reactions allergens are attached to ______.
The surface of the cell
What is the difference in allergens from Type II to III
allergens are not attached to the surface of the cell in type III.
What causes immune complex reaction or disease (type III)?
free-floating complexes that can be deposited in the tissues
What type of tissue is affected by type III free floating complexes?
joints, skin, kidney, heart, lung
Name 4 types of Type III disease
- serum sickness
- arthus reaction
- multiple sclerosis
- Type I and II diabetes
Type IV deals with which branch of the immune system
T-cell branch (all others deal with B cells)
Hypersensitivity is delayed (type IV) because
symptoms arise one to several days following the second contact with an allergen
What can we have delayed allergic reactions to? 3
infectious agents
contact dermatitis
graft rejection
A tuberculin test will produce an inflammation after how long
1 - 2 days
An individual can get contact dermatitis after exposure to ____ or ____
poison ivy or poison oak
Poison ivy affects how many people per year?
10^6 Americans/year
Poison ivy is called
Rhus spp (anacardiaceae)
The poison ivy allergen is called
urushiol
How many people are sensitive to poison ivy allergen?
50% of Americans are allergic to urushiol
Urushiol is very potent: a pinhead-sized amount could cause symptoms in _____ persons.
500
Name 5 autoimmune diseases
- Addison’s disease
- Thyroiditis
- Multiple sclerosis
- Rheumatoid arthritis
- Graves disease
