Hypersensitivity Flashcards
Types of hypersensitivity reactions
immediate: (antibody-mediated)
type i,ii,iii
delayed: (cell-mediated)
type iv
Type i: IgE- mediated
induced by allergens
1. sensitizing dose: first exposure
2. immune system produce IgE antibodies
3. IgE attach to mast cells and basophils (WBCs)
4. the next exposure to that antigen cross links IgE molecules
5. cells release granule content
Granules contain what mediators that are released during hypersensitivity?
Histamine
Leukotrienes
Prostaglandins
Cytokines
Histamine
cause smooth muscle cell constriction
Leukotrienes
potent smooth muscle constriction
Prostaglandins
constrict bronchial tubes
Cytokines
stimulate inflammation
Atopic disease (Atopy)
most common form of Type 1 hypersensitivity
common (seasonal) allergy
cause: pollen
year-round allergies can result from chronic exposure to allergens
food allergy symptoms
swollen lips
abdominal cramps
nausea
diarrhea
hives
anaphylaxis
physical factors causing hypersensitivity
extreme temp
sunlight
sweating
big eight food allergens
eggs
milk
fish
wheat
shellfish
tree nuts
peanuts
soy
Asthma
can be triggered by allergic reactions
cause: airborne allergens, exercise, cold temp
Asthma
Degranulation of mast cells
they release mediators into the lower respiratory tract causing:
Bronchoconstriction
vasodilation
mucus buildup
Asthma
recruitment of eosinophils and neutrophils into the lower respiratory tract causes:
tissue injury
airway blockage
anaphylactic shock
caused when hypersensitivity becomes systemic
anaphylactic shock s/s
1.small veins constrict
2.capillary permeability increases
3.fluid moves into tissues
4.drop in blood pressure
5.edema
6.contractions in the GI tract and bronchial muscles cause cramps and shortness of breath
possible result of anaphylactic shock
death by asphyxiation in 10-15 mins
treatments for type 1 hypersensitivity
avoidance
pharmacology
-antihistamine
-corticosteroids
-epinephrine
-antibody therapy
desensitization therapy
desensitization therapy
cause production of IgG antibodies that neutralize allergens
(Blocking antibodies) which blocks the reaction
type ii cytotoxic hypersensitivity
abtibody-mediated cell destruction
1. IgG reacts with antigens on cells
2. cells are destroyed by activated complement or by NK cells
hemolytic disease of fetus/newborn
when incompatible blood types are mixed, agglutination may occur and complement can be activated, leading to RBC destruction
Rh disease can lead to stillbirth or jundice
type iii immune complex hypersensitivity
problem is the immune complexes which get stuck and the complement system gets activated resulting in tissue damage
1.antigen-antibody aggregates form
2.complment is activated
3.tissue damage results
type iv cell mediated (delay-type) hypersensitivity
induration (thickening of skin tissue) due to cellular infiltration of immune lymphocytes
surrounded by erythema
response to certain microbial antigens
this is why TB skin test take so long (their delayed)
contact dermatitis
develops after exposure to an allergen
repeated exposures cause:
drying of skin
erythema
scaling
tick bites can cause meat allergy
lone star tick
1.bite exposes person to alpha-galactose(anitgen found in mammalian meat, cows milk, gelatin)
2.IgE antibody develops
result of the lone star tick bite
hives
swelling
*anaphylactic response a few hours after eating beef or pork
