3.2 Hypersensitivity Flashcards
Anaphylactic (type I) reactions are caused by the Antibody class _____
IgE
____ is Important for class switching to IgE and ____ also plays role
IL4, IL13
______ are antigens that increase the production of IgE
Allergens
Mast cells and basophils have high affinity ____ receptors for IgE which may remain attached for months
Fc
IgE remains isolated in blood for ________, but can remain attached to leukocytes for _____
a few days, months
how is IgE activated?
- IgE attaches to mast cell or basophil which expresses high affinity receptor FcER1
- IgE on mast cell or basophil interacts w/ specific allergen and mast cell becomes activated upon second exposure
- mast cell then releases mediators
what else can interact w/ mast cells and cause release of mediators?
anaphylatoxins
what happens during a second exposure to an allergen?
Immediate hypersensitivity rxn within minutes (found in granules) AND late phase rxn within 2-8 hours (produced by mast cell in membrane)
_______ causes Capillary dilation (blood vessels enlarge), increase in vascular permeability (get fluid rushing into tissue), and causes smooth muscle contraction
Histamine
_______ is the eosinophil chemotactic factor of anaphylaxis
ECF-A
what is found in granules during allergic reaction stimulation? what is newly synthesized?
- granules: histamine, ECF-a
-Newly syn: leukotrienes
when an allergen is inhaled in an asthmatic, there is an Immediate response due to _____ and late response due to _____
histamine, leukotriene
when does the first phase of reaction to allergen occur in an asthmatic?
30 mins
what can mast cell activation and granule release cause in the:
1. GI tract
2. Airways
3. Blood vessels
- diarrhea/vomiting
- phlegm/coughing
- increased lymph flow, edema, inflammation
what are some examples of Atopic/local v systemic anaphylaxis
atopic = asthma, allergic thinitis
systemic = anaphylactic shock
In asthma, a chronic condition is developed where _____ play a major role
eosinophils
what happens in an acute response of asthma?
- Mucosal mast cell captures antigen
- antibody response by producing IgE
- inflammation causes SM to contract, increase in mucus secretion, increase in blood vessel permeability
4.Cytokines produced bring in eosinophils
why do systemic anaphylaxis reactions happen?
systemic release of histamine and leukotrienes resulting in a generalized increase in vasopermeability, vasodilation and smooth muscle contraction
what are treatments for local vs systemic anaphylaxis?
-Local: antihistamine (blocks histamine and reverses symptoms)
-Systemic: epinephrine (decreases VP, VD, SMC)
________ are seen in allergy testing and insect bites
Wheal and flares
__________ is a treatment plan that gives you small amount of what you’re allergic to over time
Hypo-sensitization treatment
how does hypo-sensitization treatment work?
-IgE antibody starts to decrease over time
-IgG (blocking antibody) is produced over time in tissue fluid that has a chance to interact w/ allergen causing a problem before it can interact w/ IgE on mast cell
what are 4 examples of IgE mediated allergic reactions?
Systemic anaphylaxis
Wheal and flare
Allergic rhinitis
Bronchial asthma
____________ refers to an antibody-mediated immune reaction in which antibodies (IgG or IgM) are directed against cellular or extracellular matrix antigens, resulting in cellular destruction, functional loss, or tissue damage.
Type II hypersensitivity reaction
what are 4 examples of type II hypersensitivity reactions?
Blood transfusion reaction
Drug reactions
Autoimmune hemolytic anemia
Antibody-dependent cell cytotoxicity (ADCC)
___________ occurs when a patient develops antibodies against their own RBCs
Autoimmune hemolytic anemia
Patient response to therapy directed against B cells employing an anti-CD20 antibody Rituximab, is an example of which type of Type II reaction?
ADCC
____________________ are initiated by antigen-antibody complexes which can induce an inflammatory response
Immune complex disease (type III hypersensitivity)
Antigen + antibody = antigen-antibody complex and can activate the _______
complement system
_____ is chemotactic for neutrophils and can attract neutrophils to area where immune complex is
C5a
what is an example of a local Type III reaction?
Arthus reaction
what happens in an arthus reaction?
- Circulating antibodies are present
- React w/ antigen introduced subsequently
- Immune complex form within the blood vessel walls
- C’ activation and binding of immune complex to mast cell results in inflammatory response
how long does an arthus reaction take to occur?
5-6 hours
what can cause an arthus reaction?
vaccines
explain what happens in a type III systemic reactio
- Antigen-antibody complexes circulate throughout bloodstream and settle in organs, like the kidney
- this initiates inflammatory response
- Neutrophils try to remove antigen-antibody complexes and destroy filtration system of kidney → renal failure if it goes on for too long
what is an example of a systemic type III hypersensitivity reaction?
serum sickness
