hypersensitivity reactions Flashcards
Hypersensitivity Reactions defined as
Excessive responses to certain antigens
most common allergy?
type 1 response
what does sudden re-exposure antigen mean?
that the first time the person comes in contact with the anitgent they are okay but when ‘re-exposed’ they represent with allergy
what type of mediated response is type 1?
IgE
give a local reaction of type 1?
hay fever, asthma
give a systemic type 1 reaction?
anaphylactic shock
what are mast cells and basophils?
granulocytic leukocytes
what do granules contain?
serotonin, bradykinin, histamine, prostaglandins, and chemotactic factors
activities of mast cells and basophils
production/release of mucus, closure of airways, inflammation, smooth muscle contraction, shock
stage 1 of type 1 response is known as?
sensitization
sensitization stage is when?
First exposure to antigen IgE is produced instead of IgM Attaches to mast cells or basophils by Fc No release of mediators at this time No indication that anything has happened System has been primed
stage 2 of type 1 reaction is?
mediator release
what happens in the mediator release stage?
subsequent exposure to the same antigen
Cross linking of surface IgE
Mediator release
Effects due to where the reaction occurs
presentation of type 1 systemic reaction?
rapid shock/death
presentation of type 1 local reaction Allergic rhinitis (hay fever):
?
upper resp tract
presentation of type 1 local reaction Asthma:
targets trachea and bronchi
presentation of type 1 local Dermatitis (urticaria)?
targets skin
white swellings (wheals)
red itchy lesions (hives)
scaly lesions (eczema)
how to Desensitization the persons of the allergen
-Allergy shots
-Inject small amount of allergen
-Try to tie up IgE so the molecules don’t cross react
-Risk of reaction is there
-In severe cases of allergy, may be better than
actual reaction
why is IgE still produced?
parasites
Type 2 involved what cell response?
complement mediated destruction of cell associated antigens
“cell associated cytotoxicity”
which Ig’s are used in type 2 response?
G or M
C3a and C5a do what?
anaphylotoxins
increased inflammation
increased vascular permeability
C3a and C5a are present in which HSR?
2
example of type 2?
ABO transfusion reactions and Rh incompatibility
Type 3 involve which kind of mediated reactions?
deposited immune complexes
immune complex disorder refers to?
type 3
when Soluble antigens combine with antibodies to form complexes
this refers to which HSR?
3
when do antigens become a problem when talking about a type 3 HSR?
when are out of the solution
when is the complement activated in a type 3?
when the anitgen settle out
local reaction of type 3
Arthus Reaction
for type 3 Systemic reactions:
serum sickness
type 4 is what type of reaction
cell mediated
“delayed hypersensitivity reactions”
T cells and Macrophages take
take how long to respond in a type 4?
24-48 hours to respond
