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37 Cards in this Set
- Front
- Back
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hypersensitivity reaction
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overreactive immune response against foreign antigens which fails to maintain self-tolerance resulting in tissue damage
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anaphylactic reactions
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type 1 IgE Mediated reactions
occur in susceptible persons who are highly sensitized to specific allergens |
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anaphylactic reactions continued
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reaction occurs within minutes
can be life threatening (bronchial constriction & vascular collapse) shock |
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shock
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rapid, weak pulse
hypotension dilated pupils dyspenea cynosis bronchioedema/angioedema |
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atopic reactions
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an inherited tendency to become sensitive to environmental allergens
common: allergic rhinitis, asthma, atopic dermatitis, urticaria & angioedema |
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Type II: Cytotoxic/Cytolytic Reactions
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*direct binding of IgG or IgM antibodies to an antigen on cell surface
*activates complement system |
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What is destroyed with type II reactions
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*erythrocytes
*ABO/rh factor antigens *platelets *leukocytes |
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agglutination
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clumping of cells that block small blood vessels
ex: incompatible blood transfusion |
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Hemolytic transfusion reactions
(type II) |
reaction occurs when a recipient receives ABO incompatible blood
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Goodpasture Syndrome
(type II) |
circulating antibodies combine with tissue antigen to activate complement, which causes deposits of IgG to form along the basement membranes of the lungs or kidneys
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Type III: Immune-complex reactions
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complexes deposit in tissue or small blood vessels which cause the fixation of complement and release of chemotactic factors that lead to inflammation & destruction of involved tissue
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Type III: Immune-complex reactions
continued |
local or systemic
immediate or delayed response common sites for deposit: kidneys, skin, joints, blood vessels & lungs autoimmune disorders: rheumatoid arthritis, acute glomerulonephritis, systemic lupus erythematosus |
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Type IV: Delayed Hypersensitivity reactions
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cell mediated immune response (tissue damage)
24-48 hours for response bacterial, fungal or viral infections & transplant rejections |
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Contact dermatitis
(type IV) |
reaction occurs when the skin is exposed to substances that easily penetrate skin and combine with epidermal proteins
48 hours rubber compounds, cosmetics, poison oak/sumac, dyes |
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microbial hypersensitivity reactions
(type IV) |
TB
organism does not damage lung tissue- antigenic material released from tubercle bacilli reacts with T lymphocytes initiating a cell mediated immune response |
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Histamine
(type/source |
Mast cell and basophil granules
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Histamine
Biologic Response |
Increases vascular permeability; constricts smooth muscle; stimulates irritant receptors
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Histamine
Clinical Outcome |
Edema of airways and larynx; bronchial constriction; urticaria, angioedema, pruritus; nausea, vomiting, diarrhea; shock
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Leukotrienes
Type/source |
Metabolites of arachidonic acid by lipoxygenase pathway*
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Leukotrienes
Biological Activity |
Constrict bronchial smooth muscle; increase vascular permeability
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Leukotrienes
Clinical Outcomes |
Bronchial constriction; enhanced effect of histamine on smooth muscle
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Prostaglandins
Type/Source |
Metabolites of arachidonic acid by cyclooxygenase pathway*
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Prostaglandins
Biological Activity |
Stimulate vasodilation; constrict smooth muscle
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Prostaglandins
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Wheal-and-flare reaction on skin; hypotension; bronchospasm
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Platelet-Activating Factor
Type/Source |
Mast cell
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Platelet-Activating Factor
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Aggregates platelets; stimulates vasodilation
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Platelet-Activating Factor
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Increase in pulmonary artery pressure; systemic hypotension
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Kinins
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Kininogen
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Kinins
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Stimulate slow, sustained smooth muscle contraction; increase vascular permeability; stimulate secretion of mucus; stimulate pain receptors
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Kinins
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Angioedema with painful swelling; bronchial constriction
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Serotonin
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Platelets
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Serotonin
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Increases vascular permeability; stimulates smooth muscle contraction
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Serotonin
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Mucosal edema; bronchial constriction
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Anaphylatoxins
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C3a, C4a, C5a from complement activation
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Anaphylatoxins
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Stimulate histamine release
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Anaphylatoxins
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Same as for histamine
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EMERGENCY MANAGEMENT: Anaphylactic Shock
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• Ensure patent airway.
• Remove insect stinger if present. • Epinephrine 1:1000, 0.2-0.5 ml subcutaneously for mild symptoms; repeat at 10- to 15-minute intervals. • Epinephrine 1:10,000, 0.5 ml IV at 5- to 10-minute intervals for severe reaction. • Administer high-flow oxygen via non-rebreather mask. • Place recumbent and elevate legs. • Keep warm. • Administer diphenhydramine (Benadryl) IM or IV. • Administer histamine H2 blockers such as cimetidine (Tagamet). • Maintain blood pressure with fluids, volume expanders, vasopressors |
