Changes

Type I Hypersensitivity (view source)

Revision as of 11:33, 29 August 2008

477 bytes removed , 11:33, 29 August 2008

no edit summary

Line 12: Line 12:

* Ranges from mild cases, such as hayfever, to life-threatening reactions, such as bee-stings.

* Antigens that induce a type I reaction are known as allergens.

−

* ~~Affects~~ face, eyes, nose and feet

+

* Generally affects face, eyes, nose and feet

* IgE has a high affinity to IgE receptors on mast cells and basophils, and so binds these receptors.

−

* The individual mechanisms of cell degranulation may only have a marginal effect, but the combination can be highly effective in removing parasite infection

−

* Eosinophils can also target IgE bound to helminths.

−

** May either be attracted to the site of inflammation or produced de novo in response to cytokines.

−

** Binding triggers their degranulation.

−

*** Potent biological molecules are released.

−

**** Eosinophil peroxidase.

−

**** Eosinophil basic protein.

−

* This system can be invoked with inappropriate and innocuous antigens.

−

** E.g. pollen.

−

** Under these circumstances we get hay fever.

−

==Common allergens:==

+

==Common allergens which elict a type I hypersensitivity reaction:==

* Proteins : Foreign serum

Line 44: Line 34:

* Allergen exposure causes IgE production.

* IgE coat mast cells by binding to Fc receptors.

+

* Mast cells are now sensitised to this particular allergen.

Mmadment

469

edits