Intro to Hypersensitivity and Type I hypersensitivity Flashcards
What is type 1 hypersensitivity known as?
immediate hypersensitivity
What is type 1 hypersensitivity mediated by?
IgE
What is an example of a type 1 hypersensitivity response?
anaphylaxis and atopy
What is type 2 hypersensitivity known as?
cytotoxic hypersensitivity
What is type 2 hypersensitivity mediated by?
Ab and complement/phagocytosis
What is type 3 hypersensitivity known as?
immune-complex mediated hypersensitivity
What is type 3 hypersensitivity mediated by?
accumulation of immune complexes and response to them
What is type 4 hypersensitivity known as?
cell-mediated (delayed type) hypersensitivity
What is type 4 hypersensitivity mediated by?
TH cells and/or CTLs
What is sensitization?
an abnormal primary response to an antigen such that on subsequent exposure, the individual mounts an excessive or abnormal secondary response that causes disease rather than immunity
What is the type of antigen that is responsible for IgE production?
allergy
What is IgE synthesized as the result of?
activated B cell and TH2 cytokine interactions
Where do IgE cells originate in?
mucosal cells
What cell is responsible for the early phase immediate type hypersensitivity reaction?
mast cells
What is an special feature of mast cells?
Fc epsilon RI
What is Fc epsilon RI?
a high affinity receptor for IgE that makes the binding almost irreversible
Where are mast cells located?
in vascular submucosal layers
What is the immediate release mediator released from mast cells during IgE mediated degranulation?
Histamine
What is the function of histamine?
increased vascular permeability and bronchoconstriction
What are the mediators released from mast cells minutes following activation of IgE?
arachadonic metabolites (prosta glandins and leukotrienes) and the platelet activating factor
What is the function of leukotrienes?
it is the same as histamine (increased vascular permeability and bronchoconstriction) just more potent
What happens hours after IgE is activated?
synthesis of IL4 and IL5
What does IL4 do?
acts on T helper 0 to change to T helper 2s and does class switching on B cells to IgE
What does IL5 do?
eosinophil activation
What is anaphylaxis?
rapid generalized mast cell degranulation followed by eosinopil degranulation
What is the initial response to mast cell degeneration in dogs?
vomiting and diarrhea
What is atopy?
the genetic disposition for IgE mediated hypersensitivity
What is an allergy?
a hypersensitivity reaction
What is the low grade fever, lack of appetite and lethargy the day after vaccination caused by?
proinflammatory cytokines - IL1, IL6, and TNF
Typically, when can a moderate proinflammatory cytokine response to a vaccination happen (which vaccine)?
after any of the vaccines, can happen after the first
When can type 1 hypersensitivity occur (after what vaccine)?
cannot happen after the 1st vaccine, usually after the first or third
How long does it take for a type 1 hypersensitivity reaction to occur?
15-30 minutes for reaction
Where is IgE bound in b cells?
in the transmembrane part of the cell
What are the mediators of the mast cell?
antihistimines and antileukotriens
What is the main mediator for t-cell cytokines?
IL31
What is IL31 responsible for in dogs?
itching
What are the commercial product that inhibits IL31?
cytopoint and apoquel
How does cytopoint inhibit IL31?
it inhibits the binding of IL31
How does apoquel inhibit IL31?
it affects the Jak-Stat pathway and inhibits the signal from IL31
What is the target of oral immunotherapies?
IgA - inhibit t-regulatory cells
