hypersensitivity- stiner Flashcards
what is hypersensitivity?
Exaggerated or aberrant immune response to an antigen resulting in inflammation and tissue damage
what are hypersensitivity diseases?
Disorders that are caused by aberrant immune responses.
another name for Type 1 hypersensitivity is:
allergy, atopy, or immediate hypersensitivity
when does a type 1 hypersensitivity occur?
Occurs within minutes after reexposure to antigen/allergen.
what are the characteristics of a type 1 reaction?
Rapid IgE and mast cell mediated vascular and smooth muscle reaction
give examples of type 1 reactions
hives, hay fever, food allergies, bronchial asthma, anaphylaxis.
what is the first step in a type 1 reaction
Initial exposure to antigen and production of IgE antibodies (Ab) = Sensitization.
1) TH2 cells secrete IL’s
2) TH2 cell CD40L binds to B cell CD40
what is the second step in a type 1 reaction?
Binding of IgE Ab to Fc receptors on mast cells
what are the immediate and late responses of a type 1 hypersensitivity reaction
A) Immediate Effects
—Dilation of blood vessels, increased vascular permeability, smooth muscle contraction (immediate reaction).
B) Late Response
—Inflammation (late phase reaction).
Mast cell degranulation
Immediate Response
- Vasoactive amines (histamine and serotonin) and proteases
- Synthesis and secretion of lipid mediators (prostaglandins and leukotrienes made from arachidonic acid)
what are the 2 lipid mediators in type 1 reactions?
Prostaglandins and Leukotrienes
prostoglandins cause what to occur?
vasoconstriction in the lungs or dilation in vascular smooth muscle
leukotrienes are made by what process? what do they induce?
- Made via the lipoxygenase pathway
- powerful inducer of bronchoconstriction, increased vascular permeability, increased secretion and accumulation of mucus, and inflammatory cell infiltration into airways
what are the most common asthma signs and symptoms
coughing, wheezing and shortness of breath
what are the most common asthma triggers?
Airborne allergens, such as pollen, animal dander, mold, cockroaches and dust mites
during dust mite induced asthma, what enzyme cleaves the occludins in tight junctions?
Der P 1
what are the 2 main treatments for asthma?
1) Inhaled corticosteroids- These medicines are the most effective long-term control medicine
2) Leukotriene modifiers- These medicines help block the chain reaction that increases inflammation in your airways
what Determines the Type of IgE-mediated Allergic Rxn that occur?
the dose and route of entry
type 1 hypersensitivity key points
1) All clinical and pathologic features of immediate hypersensitivity reactions are driven by mediators produced by mast cells.
2) The most severe form of immediate hypersensitivity is anaphylaxis.
what is anaphylaxis
1) Response driven by the systemic release of vasoactive amines and lipid mediators from mast cells
2) Causes life-threatening drop in BP accompanied by severe bronchoconstriction
3) Treated with epinephrine (vasoconstrictor and bronchodilator) and antihistamine
what is type 2 hypersensitivity?
A) antibodies produced by the immune response that bind to antigens on our own cell surfaces
—Primarily IgG and IgM isotypes
B) host Ab binds foreign Ag on cell surfaces
or binds self Ag
C) can activate complement resulting in membrane attack complex formation
—leads to destruction of cells, inflammation, or interfere with normal cellular function
what is Hemolytic Disease of the Newborn (Erythroblastosis fetalis)
Maternal Ab’s target fetal RBC’s for destruction
what is Hemolytic anemia?
Auto-antibodies are produced against self Ag’s on the surface of RBC’s. This triggers the rapid destruction of RBC’s leading to anemia
Grave’s Disease
TSH receptor Ab’s stimulate TSH receptor to over produce thyroid hormone