Immuno: Hypersensitivity Flashcards
Hypersensitivity:
-Immune and inflammatory responses that are an over reaction of the immune system
-caused by allergens
Allergic reactions =
Subtype of hypersensitivity
Only 20% of population reacts to allergens, what causes those two percent to be allergic:
-genetic predisposition
-hygiene hypothesis
Genetic predisposition to allergens:
IL-4 receptor modification causes a lot of class switching leading to an abnormal level of IgE being produced
Hygiene hypothesis for 20% of population reacting to allergens:
Less burden of helminths/worms -> high levels of IgE body
Type 1 hypersensitivity is also called:
Immediate hypersensitivity
Type 2 hypersensitivity is also called:
Antibody-dependent hypersensitivity
Type 3 hypersensitivity is also called:
Antibody antigen complex hypersensitivity
Type 4 hypersensitivity is also called:
Cell-mediated or delayed hypersensitivity
Type 1-3 hypersensitivity is ____ mediated
Ab
Type 4 hypersensitivity is _____ mediated
T-cell
Type I hypersensitivity is an allergic reaction provoked by..
Reexposure to a specific antigen, where exposure may be ingestion, inhalation injection or direct contact
Type I hypersensitivity causes an inflammatory responses leading to an immediate reaction within…
Seconds to minutes
Type I hypersensitivity reactions can be either _______ or __________ with symptoms ranging from mild ____________ to sudden death from __________________
Local, systemic, irritation, anaphylactic shock
First exposure to allergen in type I hypersensitivity:
IgE is made by activated B cells (via IL-4) in response to allergen
What is the key cytokine for production or “switching” to IgE?
IL-4
After the first exposure in type I hypersensitivity there is a priming stage. What occurs?
Binding of IgE to Fc elipson receptor 1 on the surface of mast cells and basophils
Second exposure to allergen in type I hypersensitivity:
Antigen cross-links IgE on the surface of mast cells, causing the release of the granule’s contents
In type I hypersensitivity, after the second exposure, degranulation occurs which causes the release of ____________ and other inflammatory mediators such as __________ and ____
Histamine, proteases and TNF
Early symptoms of a type I hypersensitivity reaction:
-degranulation releasing histamine
-synthesis/release of leukotrienes and prostaglandins
-edema, redness, itching
Type II hypersensitivity is also known as _____________ hypersensitivity
Cytotoxic
What antibodies are produced by the immune system to bind antigens on the patients own cell surfaces in type II hypersensitivity?
IgG and IgM
Reaction time for type II hypersensitivity
Minutes to hours
Diseases related to type II hypersensitivity all have a common theme:
Antibodies are directed against tissues or cells of our own body