Hypersensitivity

Question 1

hypersensitivity

Answer 1

inappropriate/heightened immune response to antigen

3 pillars

• cell mediated or humoral
• results in tissue injury
• pre-sensitized host. exposed to allergen once before.

Question 2

type I hypersensitivity

Answer 2

immediate
AKA allergy
main effectors: mast cell/basophil; IgE; histamine

Question 3

atopy

Answer 3

genetic predisposition to allergic reaction

abnormal IgE production; abnormal affinity of Ab to basophils

Question 4

mechanism of injury - type 1

Answer 4

primary: body sees allergen, no reaction. b-cell sees antigen makes memory and plasma cells = IgE antibody.

secondary = second allergen present - allergen binds to sensitized mast cell = degranulation = release of histamine which causes effect of different parts of body

Question 5

type 1 - primary mediators

Answer 5

deal with degranulation effect. key effects of immunological response.

• histamine
• serotonin
• eosinophils & neutrophils
• protease

Question 6

type 1 - secondary mediators

Answer 6

make reaction last longer

• leukotrines
• PG
• bradykinin
• platelet activating factor
• cytokines

Question 7

type II

Answer 7

antibody mediated hypersensitivity

Question 8

type II main effectors & effector function of Ab

Answer 8

IgG IgM
complement
phagocytes

lyse bacterial walls trough MAC-Attack Complex
opsonie bacteria englulfed more readily

Question 9

type II mechanism - secondary response

Answer 9

1. bind allergen to surface of cell
2. stimulation
3. antibody bind to cell = immediate reaction
4. opsonic phagocytosis & antibody dependent cellular cytotoxicity (ADCC) = influence lysis by protein. complement proteins activate - opsonization, increase phagocytes in area, MAC-Attack Complex.

Question 10

Type II Disease

Answer 10

HDN - hemolytic disease of the newborn
Rh- mom and rh+ baby. first time IgG antibodies develop. nd rh+ baby - IgG Ab cross placenta and can attack baby. = inappropriate development.
treat = immunnoglobulin shot.

Question 11

type III main effectors

Answer 11

immune complex hypersensitivity

main effectors: Ag-Ab complex; complement; inflammation

Question 12

type III - physical responses & clinical manifestations

Answer 12

large complexes deposit in kidneys, microvasculature = vasculitis, nephritis, arthritis

local = arthus reaction = fungal spores inhaled, complex in lungs.

acute systemic = serum sickness - add wrong blood type into blood.

chronic systemic = SLE; rheumatoid arthitis

Question 13

Type IV : main effectors

Answer 13

cell mediated: delayed.
CD8 t-cell = cytotoxic.
macrophage= infiltrate - injury to tissue

Question 14

t-cell effector function

Answer 14

bacterium presents antigen - act on CD4 helper cell. with MHC complex.
cytotoxic CD8 cll kills cell thru activation of immune system. CD8 kills APC - which is CD4 in this case. osmotic lysis.

CD4 also act on their own - pre-cytotoxicity - to increase phagocytes, proliferate t-cell and increase edema ==> takes time. inflammation by phagocytes

Question 15

clinical manifestation of type IV

Answer 15

contact dermatisis - poison ivy
chronic infectious diseases: viral hepititis
acute rejection of transplant