Lecture 28: Type II-IV Hypersensitivities Flashcards
Type II hypersensitivity reactions occur through production of what Ig’s
IgM or IgG
What type of hypersensitivity reactions are myasthenia gravis and Pemphigus
Type II
What happens during sensitization phase of type II hypersensitivity reactions
Exposure to antigen leads to production of IgG or IgM
What occurs during effector phaser of hypersensitivity reactions
Re-exposure to antigen allows allergen specific IgM or IgG to bind causing immune mediated damage or blocks normal function of cells/tissues
What are some effector phase mechanisms in type II hypersensitvities
ADCC, complement mediated lysis (MAC), and antibody interference
What type of hypersensitivity is secondary IMHA
Type II
What causes secondary IMHA
Immunologic response against non-self antigens that have absorbed or modified normal RBC’s
Antibodies bind to antigens on RBC’s resulting in lysis
What type of hypersensitivity reaction are transfusion reactions
Type II
What causes transfusion reactions
Reaction to blood group antigens mediated by antibodies that bind and lyse transfused RBC’s
What tests should be run to prevent transfusion reactions
Blood typing and cross matching
What type of hypersensitivity reaction is neonatal iseoerthyrolysis
Type II
What causes neonatal iseoerthrolysis
Foal is Aa+ and mare is Aa- therefore producing anti-Aa antibodies in milk, resulting in mismatched blood group maternal antibodies that bind and lyse neonatal RBC’s
What commonly causes maternal AB’s to arise and cause neonatal isoerythrolysis
Repeated pregnancies
What are some diagnostic tests that can be performed for type II hypersensitivities
ELISA and direct Coombs test
What is the ELISA test testing for
Antibodies
How does the direct Coombs test work
Detects antibodies bound to RBC’s, agglutination assay
Type III hypersensitivities are reactions caused by ___formed by ___
Small immune complexes formed by soluble antigens
What Ig’s are released in type III hypersensitivity
IgG or IgM
What causes small aggregates/complexes
Exposure to antigen or antibody excess
SLE is example of what type of hypersensitivity
Type III
What happens in sensitization phase of type III hypersensitivities
Initial exposure to antigen resulting in immune complexes that deposit into tissues
What happens in effector phase of type III hypersensitivity reactions
Immune complex activation of complement and recruitment of inflammatory cells
Immune complexes in type III hypersensitivity reactions accumulate in tissue and cause continual activation of ____ and release of ___ and ____
Complement, neutrophils and ROS
Platelet aggregation and possible development of thrombi, hemorrhage, edema and necrosis in tissues could be a result of what type of hypersensitivity reaction
Type III
What type of hypersensitivity reaction is Arthus reaction
Type III
What causes arthus reaction- localized vasculitis
Sensitization of antigen results in high levels of antibody production leading to antibody excess
Upon repeated exposure antibodies form small immune complexes and deposit in vasculature at exposure site
What are some examples of arthus reactions- localized vasculitis
Canine blue eye, hypersensitivity pneumonitis, equine RAO
What causes systemic vasculitis (serum sickness)
Large dose of foreign serum or in response to some infection—> antigen excess
Where do small immune complexes in systemic vasculitis form
Vessel walls
Systemic immune complex deposition result in tissue damage and what are 3 common manifestations
Vasculitis, arthritis, glomerulonephritis
What vaccine in horses can cause purpura hemorrhagica
Strangles, immune response to bacterial M protein
What is a diagnostic test that can be used in type III hypersensitivities
ELISA immunoassays
What are some possible treatments for type III hypersensitivities
Corticosteroids, antibiotics, and supportive care (IV, NSAIDS)
What cells mediate type IV hypersensitivity reactions
TH1, macrophages, and cTL’s
Type IV hypersensitivity reactions are often caused by what complexes
Hapten carrier
What happens during sensitization phase of type IV hypersensitivity reaction
Primary immune response
What happens during effector phase of type IV hypersensitivity reaction
Activation of memory Th1 cells
What cytokines are released by Th1 in type IV effector phase
IFN-y and IL-8
Recruitment an activation of macrophages and neutrophils in type IV effector phase result in tissue destruction due to ___ and ___
Lytic enzymes and ROS
Prolonged Type IV hypersensitivity reactions can lead to ___formation
Granuloma
Turbecule formation is an example of what type of hypersensitivity reaction
Type IV
What in vivo testing can be done for TB
Intradermal tuberculin testing
What proteins are injected in TB skin test
Tiubuerculin proteins
What in vitro testing can be done for TB
IFN-y release assay, measure release by T cells
How would you perform IFN-y release assay for TB
Obtain blood, add antigen, centrifuge, remove supernatant, measure IFN-y with ELISA
What type of hypersensitivity reaction is contact dermatitis
Type IV
What complex forms with contact dermatitis
Hapten that complexes with protein
Contact dermatitis is characterized by
Eczematous, blistering reactions
What tests can be done for contact dermatitis
patch test, small square impregnated with suspected allergen
What indicates a positive patch test
Redness, edema, formation of vesicles
