Quiz 2 Exam 4 Flashcards
Hypersensitivity and allergies (146 cards)
Hypersensitivity is an _____________ of the immune system
Over-reaction
Hypersensitivity reactions are immune reactions that are __________ against an _________.
Exaggerated
Antigen
In the classification of hypersensitivity reactions by Coombs and Gell, what is the mechanism behind type I/ immediate type hypersensitivity reactions?
Type 1 hypersensitivity reactions are IgE mediated with mast cells and basophils. This response can be rapid or delayed
In the classification of hypersensitivity reactions by Coombs and Gell, what is the mechanism behind type II/ antibody-mediated cytotoxic hypersensitivity reactions?
Type II hypersensitivity reactions are IgG and IgM mediated. This response can be from hours to days.
In the classification of hypersensitivity reactions by Coombs and Gell, what is the mechanism behind type III/ immune complex mediated hypersensitivity reactions?
Type III hypersensitivity reactions are mediated by antigens and antibodies as well as IgG and IgM. This response can take hours to weeks.
In the classification of hypersensitivity reactions by Coombs and Gell, what is the mechanism behind type IV/ T cell-mediated hypersensitivity reactions?
Type IV hypersensitivity reactions are mediated by T lymphocytes and cytokines. This reaction can last days to weeks.
The initial exposure in type I hypersensitivity reactions is due recognition of T cells and presentation of MHC molecules which stimulates plasma cells to produce __________. That will binds to basophils and mast cells and stimulate the release of granules with inflammatory mediators.
IgE
When IgE binds to mast cells and basophils in the type I hypersensitivity reaction, what mediators are released in response?
Granules and inflammatory mediators
What are some of the different mediators released by mast cells?
They release preformed mediators like histamine, heparin, proteases, and TNF. THey release lipid mediators like prostaglandins and leukotrienes, and they release cytokines and chemokines.
What are the main actions of the different mediators released by mast cells in a type I hypersensitivity reaction?
Vasodilation, increased vascular permeability, smooth muscle spasms, and leukocyte extravasation.
Cytokine releases increases vascular permeability which shifts fluid from intravascular to extravascular space. What is the result of intravascular depletion?
This results in decreased perfusion of tissues and organs. It also decreased blood pressure and reflexively increases heart rate.
Cytokine releases increases vascular permeability which shifts fluid from intravascular to extravascular space. What is the result of extravascular accumulation?
Edema
Allergy is a hypersensitivity reaction in which ________________ mediated hypersensitivity is prominent.
IgE
Thinking about drug allergies, what is the main thing to determine in patients?
Identify patients at risk for hypersensitivity reactions.
What is the physiology surrounding anaphylaxis?
Mast cells suddenly release a large amount of histamines and leukotrienes which leads to intense bronchospasms, laryngeal edema, cyanosis, hypotension, and shock.
In a very basic sense, anaphylaxis is a very severe __________ hypersensitivity reaction.
Type I
What is the clinical criteria for an anaphylaxis diagnosis?
- Acute onset of the illness with involvement of skin, mucosal tissue, or both
- ONE OF THE FOLLOWING
A. Respiratory compromise
B. Reduced BP or symptoms of end-organ dysfunction
C. Severe GI symptoms
What are the 3 goals in the management of type I hypersensitivity reactions?
- Inhibit mast cell degranulation
- Antagonize mast cell mediators
- Reduce inflammation
What is the main drug given in anaphylaxis?
Epinephrine
What are the effects of epinephrine?
VAscular smooth muscle cell contraction, increases cardiac output, inhibits bronchial smooth muscle cell contraction
How is anaphylaxis managed long-term?
Identify the triggers and create a written action plan. Educate the patient and makes sure they have epi pens. All about preventing the recurrence to prevent death.
What is the pathophysiology behind a type II hypersensitivity reaction?
Type II hypersensitivity reactions are antibody-mediated cytotoxic reactions. It is when IgG and IgM antibodies produced by immune responses bind to antigens on the individuals own cell surface. When these large immune complexes are formed, they can initiate the complement cascade.
Cellular destruction in type II hypersensitivity reactions occur via what 3 mechanisms?
Phagocytosis
Complement-dependent cytotoxicity (CDC)
Antibody-dependent cellular toxicity (ADCC)
What is the pathophysiology behind type III immune complex mediated hypersensitivity reactions?
There is an accumulation of antigen-antibody complexes (immune complexes) that are NOT cleared by innate immune cells. The immune complexes lead to complement activation and inflammatory responses mediated by neutrophils.