Allergies (ch. 22) Flashcards
Most common type of hypersensitivity
Type 1, or rapid. Also called atopic allergy.
Results from increased production of IgE (allergieeeeeee) responds to antigen such as pollen, and causes release of histamine and other vasoactive amines from basophils, eosinophils (allergieeeeeosinophils), and mast cells.
Type 1 reactions
Anaphylaxis and allergic asthma.
Atopic allergies such as hay fever and allergic rhinitis
Specific allergens such as latex, bee venom, peanuts, iodine, shellfish, drugs, and thousands of other environmental allergens.
Define anaphylaxis
Widespread blood vessel dilation, decreased cardiac output and bronchoconstriction.
Type 2 reactions
“Cytotoxic”
Body makes special auto antibodies directed against self cells that have some form of foreign protein attached to them.
Autoantibody binds to self cell and forms immune complex
Self cell is destroyed along with protein by phagocytosis
Treatment: d/c offending drug or blood product, plasmapheresis.
Type 3 reactions
“Immune complex reaction”
Excess antigens cause immune complexes to form in blood. They lodge in small blood vessel walls of kidneys, skin, joints, and other small blood vessels. Deposited complexes trigger inflammation and tissue or vessel damage results.
Ex: RA, SLE, glomerulonephritis, arthralgia, arthritis all caused by type 3 rxn.
Type 4 reactions
“Delayed hypersensitivity rxn”
Sensitzed T-cells respond by triggering macrophages to destroy antigen.
Occurs hours to days after exposure.
Rxn is edema, induration, ischemia and tissue damage at site.
Example: PPD test (raised skin w/redness), contact dermatitis, poison ivy skin rash, insect sting, tissue transplant rejection, sarcoidosis.
Type 5 reaction
“Stimulatory rxn”
Excessive stimulation of a normal cell surface receptor by an autoantibody.
Ex: Grave’s disease (autoantibody binds to TSH receptor site on thyroid gland continually stimulating thyroid cells to produce thyroid hormones causing severe hyperthyroidism).
Autoimmunity
Person developed an inappropriate immune response against healthy, normal cells and tissues.
Ex: SLE, RA, rheumatic fever, Hashimoto’s thyroiditis, Type 1 Diabetes
