Immune System Gone Wrong: Part 1 Flashcards
Type I hypersensitivity reaction is mediated by..
IgE antibodies
Type II hypersensitivity reaction is mediated by…
IgG or IgM antibodies
Is a Type II hypersensitivity reaction cytotoxic?
Yes
Type III hypersensitivity reaction is mediated by…
Immune complexes
Type IV hypersensitivity reactions are mediated by…
Cellular response
Are Type IV reactions immediate or delayed?
Delayed
What is the acronym to remember the four different types of sensitivity reactions?
ACID
What are the two stages that hypersensitivity reactions go through?
- Sensitization stage
- Effector stage
When does the sensitivity stage occur?
During the first exposure an individual has to an antigen
What happens during the sensitization stage for Type I hypersensitivity reactions?
Mast cells and basophils become sensitized to the allergen
What happens during the sensitization stage for Type II hypersensitivity reactions?
Production of antibodies to recognize substances
What happens during the sensitization stage for Type III hypersensitivity reactions?
Presence of antibodies against the offending antigen in the serum of affected individuals
What happens during the sensitization stage for Type IV hypersensitivity reactions?
T cells are sensitized and memory T cells are produced, 7-10 days later
What is the effector stage?
Second or subsequent exposure to the antigen
What stage causes damage to the host?
Effector/secondary immune response
What type of hypersensitivity starts immediate allergic reaction?
Type I
What type of hypersensitivity uses Th2?
Type I
What is atopy?
Hereditary predisposition to the development of immediate hypersensitivity reactions
Atopy tends to produce what antibody in excess to extremely small amounts of naturally occurring allergens?
IgE
Atopic individuals have abnormally high levels of what type of immune cell?
Eosinophils
What individuals are more susceptible to allergies such as hay fever, eczema, and asthma?
Atopy individuals
What is localized IgE-mediated hypersensitivity?
Affects a specific target tissue
What are three examples of localized IgE mediated hypersensitivity?
- Asthma
- Eczema
- Hay fever
What are three examples of systemic IgE mediated hypersensitivity?
- Venom
- Drugs
- Food
What is systemic IgE-mediated hypersensitivity?
- Affects the whole body
- Anaphylaxis
When can an allergen crosslink the IgE molecules bound on a mast cell?
During subsequent exposure
What tells mast cells to degranulate?
Clustering of IgE receptors
What is released from mast cells and basophils?
Histamine
What does histamine do?
Vasodilate blood vessels
What cell plays a large role in chronic allergic reactions?
Eosinophils
What can lead to mast and basophil cell degranulation?
Crosslinking of IgE antibodies
What does a non-allergic person do?
Does not response to antigen or eliminates allergen with IgG, IgM, or IgA
What is the hygiene hypothesis?
Children who are exposed to bacteria are less prone to developing allergies
How is Treg cells involved in suppressing allergic reactions?
- Block mast cell activation
- Block interleukin production
- Block B cells from making IgE
- Release pre-formed anaphylactic mediators
What are the two types of treatments for allergies?
- Glucocorticoid steroids
- Specific immunotherapy
How do glucocorticoid steroids decrease allergy symptoms?
Block cytokine production of helper T cells, fewer B cells are activated
Are glucocorticoid steroids specific for treating allergies?
No
What is the only cure to allergies that has been successful?
Specific immunotherapy/allergy shots
What is specific immunotherapy/allergy shots?
Injection of gradually increasing dose of crude extractions of allergen until a maintenance dose is achieved
What is the immediate result of specific immunotherapy/allergy shots?
Mast cells become more difficult to activate in response to IgE binding
Overtime, was does specific immunotherapy/allergy shots encourage?
Allergen specific B cells to switch their antibody class from IgE to another class
