unit 4 hypersensitivity reaction

Question 1

sensitization

Answer 1

first exposure to allergen that primes immune system for second exposure (acts on it the second time and you’ll experience symptoms)

Question 2

hypersensitivity

Answer 2

heightened (unnecessary) response to environmental antigen that causes tissue damage

Question 3

allergens

Answer 3

noninfectious environmental antigen that induces a hypersensitivity

Question 4

histamine

Answer 4

granule that causes allergic manifestations (symptoms)

Question 5

Type I hypersensitivity

Answer 5

immediate reaction commonly known as allergies
–> fastest response
–> anaphylaxis

Question 6

type I hypersensitivity mechanism

Answer 6

1. allergen elicits IgE response
   –> IL-4 +13 cause class switch to IgE
2. IgE binds to FC portion of mast cells using epsilon receptor
3. mast cells with IgE travel searching for allergen
4. allergen cross links 2 IgE and causes mast cell to degranulate
   –> heparin, histamine, protasglandins, chemoattractants
5. chemoattractants bring eosinophils and neutrophils for second phase
6. they also degranulate

Question 7

type II hypersensitivity

Answer 7

immediate response that is cytotoxic (targets cell) and causes cell death or altered function

Question 8

type II hypersensitivity mechanisms

Answer 8

1. IgG or IgM binds to cell surface (receptor) that it perceives as foreign
   –> can be self antigens or exogenous antigens (forming new epitope)
2. when antibody binds it can
   –> block normal function of cell receptor
   –> activate complement and opsonize for phagocytosis or go through membrane attack complex
   –> antibody-dependent cell-mediated cytotoxicity which causes apoptosis

Question 9

type III hypersensitivity

Answer 9

immediate response that involves deposition of immune complexes where antibodies bind to antigens

Question 10

type III hypersensitivity mechanism

Answer 10

1. small immune complexes formed with IgG and IgM
2. immune complexes circulate and deposit in variety of tissues
3. complement activates (classical pathway because of antibody)
4. MAC is initiated and host cells near immune complexes are lysed (split products are released)
5. neutrophils attempt to phagocytize but cannot because complexes are bound with great affinity
6. instead they release toxic granules with destroys neighboring cells

Question 11

type IV hypersensitivity

Answer 11

delayed response that involves T-cell mediated death of cells
–> think induration

Question 12

type IV hypersensitivity mechanism

Answer 12

1. initiated by CD4+ T cells which bind to antigen on MHC II APC
2. APC releases IL-12 to produce Th1 cells to drive cellular response
3. Th1 cells secrete IL-2 to cause proliferation and recruits more cells to site
4. phagocytes release proinflammatory cytokines
5. Th17 cells secrete IL-17 also recruits neutrophils
6. CD8+ cells kill target cell with prefornins

Question 13

clinical manifestations of type I hypersensitivity

Answer 13

–> anaphylactic shock
systemic and occurs throughout body
–> respiratory allergy
allergic rhinitis, asthma
–> food allergy
urticaria (hives), wheal/flare, and angioedema (swelling)

Question 14

RIST method of measuring IgE

Answer 14

measures total serum IgE

Question 15

RAST method of IgE

Answer 15

measures antigenic specific blood
–> amount of IgE specific for certain allergy

Question 16

method of immunotherapy

Answer 16

desensitization of IgE production and mast cell degranulation through small controlled doses of allergens

Question 17

type II hypersensitivities

Answer 17

1. blood transfusions
2. hemolytic disease of newborn
3. drug induced hemolytic anemia
4. myasthenia gravis
   –> immediate cell killing

Question 18

incompatible blood transfusions

Answer 18

self antibody binds and attacks donor RBC because of incompatibility of blood group or presence of Rh antigen
–> coagulopathy, kidney damage, low blood pressure

Question 19

hemolytic disease of newborn

Answer 19

mother does not have antigen but baby does. in result IgG crosses placenta and attacks RBCs Rh antigen
–> hemolytic anemia, jaundice, heart failure

Question 20

drug induced hemolytic anemia

Answer 20

drugs bind and cause cell receptors to look foreign which causes lysis of RBCs

Question 21

myasthenia gravis

Answer 21

antibodies produced against acetylcholine receptors in muscle fibers which blocks function and prevents muscles from stimulating (contracting)

Question 22

type III hypersensitivities

Answer 22

1. arthus reaction
2. farmers lung
3. serum sickness
4. glomerulonephritis

Question 23

arthus reaction

Answer 23

deposition of immune complexes leads to painful erythema and induration

Question 24

farmers lung

Answer 24

inhaled allergens cause immune complexes which lead to flu like symptoms

Question 25

serum sickness

Answer 25

patient recieves antiserum which leads to immune complexes and causes rashes, itchiness, joint pain

Question 26

glomerulonephritis

Answer 26

complication of infection that causes deposit of immune complexes of tissue in kidney

Question 27

type IV hypersensitivity

Answer 27

tuberculin reaction
contact dermatitis
granulomatous reaction

Question 28

tuberculin

Answer 28

injection under skin stimulate immune response and influx of immune cells at site causes induration

Question 29

contact dermatitis

Answer 29

proliferation at site causes welts

Question 30

granulomatous

Answer 30

formation of granulomas in which antigens are sequesters from rest of body to prevent lingering inflammation