Hypersensitivity flashcards
(23 cards)
When does type I hypersensitivity occur?
Within minutes after reexposure to antigen/allergen
What is type I hypersensitivity?
Rapid IgE and mast cell mediated vascular and smooth muscle reaction that is often followed by inflammation
What are some examples of type I hypersensitivity?
Hives, hay fever, food allergies, bronchial asthma
What is the general sequence of events for type I hypersensitivity?
Sensitization (production of IgE antibodies). TH2 cells secrete IL’s and TH2 cell CD40L binds to B cell CD40.
What is the immediate response of mast cell degranulation?
Vasoactive amines (histamine and serotonin) and proteases
What is a powerful inducer of bronchoconstriction and increased vascular permeaility?
Leukotrienes
What is the late-phase reaction of mast cell degranulation?
Synthesis and secretion of cytokines (TNF-alpha, IL-4, IL-5) and chemokines
Eosinophil granules contain what?
ROS, MAJOR BASIC PROTEIN, prostaglandins, and leukotrienes.
What are the cellular events of mast cell activation?
Allergen binds IgE on surface triggering cascade leading to release of arachidonic acid
What are common triggers of asthma?
Airborn allergens, such as pollen, animal dander, mold, cockroaches and DUST MITES
General release of histamine causing systemic anaphylaxis is a result of what dose/route of allergen entry? (IgE mediated)
Intravenous: high dose
Local release of histamine causing wheal and flare reaction is a result of what dose/route of allergen entry? (IgE mediated)
Subcutaneous: low dose
Allergic rhinitis (upper airway) caused by increased mucus and nasal irritation as well as asthma are a result of what dose/route of allergen entry? (IgE mediated)
Inhalation: low dose
Contraction of intestinal smooth muscle inducing vomiting, diahrea, hives, and anaphylaxis are a result of what dose/route of allergen entry? (IgE mediated)
Ingestion
What cell type drives type I hypersensitivity?
Mast cells
What is the most severe form of immediate hypersensitivity?
Anaphylaxis
What is anaphylaxis?
Systemic release of vasoactive amines and lipid mediators from mast cells causing life threatening drop in blood pressure accompanied by severe bronchoconstriction
What is Type II hypersensitivity?
Ab produced by the immune response bind to antigens on our own cell surfaces (IgG and IgM isotypes)
What are some examples of Type II hypersensitivity?
Hemolytic disease of the newborn
What is Type III hypersensitivity?
Ag-Ab complexes clump and deposit in blood vessels or tissues attractinga n acute inflammatory reaction
what is Type IV hypersensitivity?
Ag specific T cells which induce macrophage infiltration in a sensitized individul. (Delayed type hypersensitivity)
What are haptens?
Small molecules that must become bound to a larger carrier molecule in order to illicit an immune or inflammatory response
What type of hypersensitivity does Tb elicit?
Type IV hypersensitivity
