Immune System and Hypersensitivity Flashcards
Which antibodies are involved in type I hypersensitivity?
IgE binds to basophils and mast cells = causes histamine, arachidonic acid release
When are Type I hypersensitivities invoked?
Re-exposure to a specific antigen
What does histamine cause in Type I?
-immediate reaction due to inflammatory response
-local or systemic
-local treatment involves antihistamines and corticosteroids
-systematic can be life threatening
What are examples of Type I allergic reactions?
allergic conjunctivitis
Hay fever
Allergy to bee stings = anaphylaxis
Peanuts = anaphylaxis
Which antibodies are involved in Type II cytotoxic reactions?
IgG, IgM antibodies bind to antigens on cell surfaces or a foreign antigen resembling a molecule on the cell and trigger immune response by complement proteins
How do IgG and IgM lead to apoptosis?
-they activate the complement pathway and generate MAC, which makes a pore in the pathogen and causes lysis
-Opsonizes the cell (primes it for) phagocytosis
-Makes cell a target for Natural Killer cells
What are examples of Type II cytotoxic reactions?
-autoimmune hemolytic anemia
-blood transfusion reactions
-hemolytic disease in newborns (Rh antigens)
-hashimoto’s
Which antibodies are involved in the Type III immune complex?
Soluble IgG and IgM aggregates are deposited in various tissues (skin, kidneys, joints)
Triggers immune response by complement activation
How does Type III immune complex impact the kidneys?
The aggregates clump in nephrons and attracts complement proteins (MAC causes cell death in kidney cells and increase in cells prevents kidney filtering)
What are examples of Type III immune complexes?
-Immune complex glomerulonephritis
-rheumatoid arthritis
-systemic lupus erythematosus
What is Type IV delayed hypersensitivity?
-cell-mediated response (not antibodies)
-Takes 2-3 days to develop
-Memory T-cells are produced (and make a stronger response with subsequent exposures)
What cells are involved in Type IV reactions?
-cytotoxic T cells attach to antigen similar to foreign antigen on healthy host cell
-Tissue destruction
-Other cytotoxic T-cells are attacked by neutrophils = inflammation and neutralization of antigen
-Other T-lymphocyte receptors don’t turn into cytotoxic T-cell and just return to immune system (memory cells)
What are examples of Type IV delayed response?
-latex allergy
contact dermatitis
transplant rejection
