Hypersensitivity Reactions (Exam 2) Flashcards
A type 1 hypersensitivity reaction is also classified as an…
anaphylactic hypersensitivity reaction
A type 2 hypersensitivity reaction is also classified as an…
antibody-mediated cytotoxic hypersensitivity reaction
A type 3 hypersensitivity reaction is also classified as a…
complex-mediated hypersensitivity reaction
A type 4 hypersensitivity reaction is also classified as a…
cell-mediated hypersensitivity reaction or delayed reaction
What are the mediators of a type 1 reaction?
IgE
What are the mediators of a type 2 reaction?
IgM and IgG
What are the mediators of a type 3 reaction?
IgM and IgG
What are the mediators or type a type 4 reaction?
T cells
What type of hypersensitivity reaction has the following mechanism?
Release of mediators from IgE sensitized mast cells and basophils.
Type 1 reaction
What type of hypersensitivity reaction has the following mechanisms?
Cell destruction caused by antibody and complement, opsonization, or ADCC.
Cell function inhibited by antibody binding.
Cell function stimulated by antibody binding.
Type 2 reaction
What type of hypersensitivity reaction has the following mechanism?
Antigen-antibody complexes activate complement proteins. Neutrophils are recruited and release lysosomal enzymes that can cause tissue damage?
Type 3 reaction
What type of hypersensitivity reaction has the following mechanism?
Antigen-sensitized Th1 cells release cytokines that recruit macrophages and induce inflammation or activate cytotoxic T cells to cause direct cell damage.
Type 4 reaction
Does a type 1 sensitivity reaction involve complement?
No
Does a type 2 sensitivity reaction involve complement?
Yes
Does a type 3 sensitivity reaction involve complement?
Yes
Does a type 4 sensitivity reaction involve complement?
No
What type of hypersensitivity reaction is called a delayed reaction?
Type 4
What type of hypersensitivity reaction is due to the following antigen type?
Autologous or heterologous
Type 4
What type of hypersensitivity reaction is due to the following antigen type?
Soluble autologous or heterologous
Type 3
What type of hypersensitivity reaction is due to the following antigen type?
Cell surface autologous or heterologous
Type 2
What type of hypersensitivity reaction is due to the following antigen type?
Heterologous
Type 1
What type of hypersensitivity reaction is described by the following clinical examples?
Anaphylaxis, allergic rhinitis, allergic asthma, food allergies, and urticaria (hives)
Type 1
What type of hypersensitivity reaction is described by the following clinical examples?
Contact dermatitis, tuberculin and anergy skin tests, hypersensitivity pneumonitis
Type 4
What type of hypersensitivity reaction is described by the following clinical examples?
Serum sickness, Arthus reaction, SLE, RA, and drug reactions
Type 3
What type of hypersensitivity reaction is described by the following clinical examples?
Transfusion rejections, autoimmune hemolytic anemia, hemolytic disease of the newborn, drug reactions, myasthenia gravis, Goodpasture’s syndroms, and Grave’s disease
Type 2
Reaction characterized by deposition of ab-ag complexes in the blood vessels of skin
Arthus reaction
An acute reaction that simultaneously involves multiple organs. Clinical signs begin within minutes after antigenic challenge and may involve brochospasm and laryngeal edema, vascular congestion, skin manifestations such urticaria (hives) and angioedema, diarrhea and vomiting, and intractable shock because of the effect on blood vessels and smooth muscle of the circulatory system.
Anaphylaxis
The severity of this type of reaction depends on the number of previous exposures to the antigen resulting in an accumulation of IgE on mast cell and basophil cell surfaces.
Anaphylaxis
Symptoms develop within a few minutes to a few hours; Ab mediated
Immediate hypersensitivity
Symptoms not seen until 24-48 hours after contact with antigen; Cell mediated
Delayed hypersensitivity
What occurs when IgE binds to antigen?
Degranulation of mast cell (or basophil)
Preformed mediator of early phase symptoms that may cause vasodilation, vascular permeability, skin redness (erythema), and bronchiole obstruction.
Histamine
Preformed mediator of early phase symptoms that can keep blood from clotting.
Heparin
Preformed mediator of early phase symptoms that may attract eosinophils.
Eosinophil chemotactic factor for anaphylaxis (ECF-A)
Preformed mediator of early phase symptoms that may attract neutrophils.
Neutrophil chemotactic factor
Preformed mediator of early phase symptoms that may cause mucus production, cytokine activation, and convert C3 to C3b.
Proteases
Secondary mediator that may cause platelet aggregation, attract eosinophils and neutrophils.
Platelet activating factor (PAF)
Secondary mediator that may cause vasodilation, vascular permeability and skin redness.
Prostaglandin D2 (PGD2)
Secondary mediators that may attract neutrophils and eosinophils, cause vascular permeability, bronchoconstriction, and mucous production.
Leukotrienes
Secondary mediator that may attract neutrophils and eosinophils and increase IgE production.
Cytokines
An in vivo test that can detect hypersensitivity to a wide variety of inhaled or food allergens. A positive result is indicated by a wheal-and-flare reaction with a diameter greater than 3 to 4 mm.
Percutaneous allergy test
An in vivo test that is more sensitive and uses a greater amount of antigen. This test is sensitive to many allergens, but has no benefit in the diagnosis of food allergens.
Intradermal (tuberculin) allergy test
A noncompetitive radioimmunoassay used to detect allergen-specific IgE
RAST
A noncompetitive immunoassay used to detect total IgE
RIST
What is known to be the method of choice for most allergy specialists?
A commercial noncompetitive fluoroimmunoassay (instead of using radioactive labels)
What type of hypersensitivity used to be tested using RIST and RAST?
Type 1
Detects in vivo attachment of antibodies to the patient’s own red cells.
Direct Coombs’ Test
What type of hypersensitivity can be tested using Coombs’ test?
Type 2
Detects in vitro attachment of antibodies in the patient’s serum to a panel of reference RBCs with known antigens on their surfaces.
Indirect Coombs’ Test
Immune complex deposition in SLE occurs in multiple organs, but where does the main damage occur?
In the glomerular basement membrane of kidneys
Which autoimmune disorders are type 3 hypersensitivity?
Rheumatoid arthritis (RA) and SLE
Agglutination reaction, EIA, histological fluorescent staining, complement level testing, and antibody identification are all used to test what type of hypersensitivity?
Type 3
Tuberculin skin test for Mycobacterium tuberculosis antigen or PPD (purified protein derivative) injected under skin and read in 48-72 hours is an example of a test for what type of hypersensitivity?
Type 4
