Immunology Chapter 14 – IgE mediated immunity and allergy
Balanced immune system
Activation (inflammation)
o Non-self “the bad”
Inhibition (tolerance) – tolerant to what we already have in the body and
tolerant to harmless invaders as they do not harm the body
o Non-self “the good”
Allergies
Allergens are harmless but not everybody see this as harmless and response to
them
Allergy: is a hypersensitivity against harmless non-self-elements.
The hypersensitivity is directed by the adaptive immune system although effector
mechanisms are an interplay between innate and adaptive differentiated in different
types. 4 types:
I: occur within hours and all depend on the formation of antibodies (IgE)
Unique for allergy
II: occur within hours and all depend on the formation of antibodies (IgE). Also
depend on the production of IgE against drugs
Can also occur during transplantation, auto-immunity or extreme inflammation
III: occur within hours and all depend on the formation of antibodies (IgE). Also
depend on the production of IgE against foreign antibodies
Can also occur during transplantation, auto-immunity or extreme inflammation
IV (delayed type of hypersensitivity (DTH): occurs within several days. It is
caused by DC that stimulate CD4+ T cells.
Can also occur during transplantation, auto-immunity or extreme inflammation
IgE mediated immune responses
Activation of mast cells, baso- and eosinophils
o Mast cells: resides (bevinden) in tissues where they provide protection
Present in mucosal and epithelial tissues
Full of granules which are released upon activation
The mast cell can capture many different IgE antibodies specific for
multiple antigens
o Eosinophils: resides in the blood
Clearing of multi-cellular parasites.
Challenges of muti-cellular parasites:
- Parasites are biologically and chemically more similar to humans
compared to other pathogens
- Less antigenic
- Parasites are big cannot be phagocytosed by macrophages and
neutrophils
IL4 produced by DC --> Th2 cells produce IL4/5 --> instruct B cells for IgE
production --> IgE bind to FcER1 receptor expressed on the surface of
basophils, eosineophils and mast cells they remain inactive --> when FcER1 is
crosslinked because the Fc tail of IgE antibodies recognize their antigen
(parasite or allergen) (depot formation) they start to degranulate --> secretion
Balanced immune system
Activation (inflammation)
o Non-self “the bad”
Inhibition (tolerance) – tolerant to what we already have in the body and
tolerant to harmless invaders as they do not harm the body
o Non-self “the good”
Allergies
Allergens are harmless but not everybody see this as harmless and response to
them
Allergy: is a hypersensitivity against harmless non-self-elements.
The hypersensitivity is directed by the adaptive immune system although effector
mechanisms are an interplay between innate and adaptive differentiated in different
types. 4 types:
I: occur within hours and all depend on the formation of antibodies (IgE)
Unique for allergy
II: occur within hours and all depend on the formation of antibodies (IgE). Also
depend on the production of IgE against drugs
Can also occur during transplantation, auto-immunity or extreme inflammation
III: occur within hours and all depend on the formation of antibodies (IgE). Also
depend on the production of IgE against foreign antibodies
Can also occur during transplantation, auto-immunity or extreme inflammation
IV (delayed type of hypersensitivity (DTH): occurs within several days. It is
caused by DC that stimulate CD4+ T cells.
Can also occur during transplantation, auto-immunity or extreme inflammation
IgE mediated immune responses
Activation of mast cells, baso- and eosinophils
o Mast cells: resides (bevinden) in tissues where they provide protection
Present in mucosal and epithelial tissues
Full of granules which are released upon activation
The mast cell can capture many different IgE antibodies specific for
multiple antigens
o Eosinophils: resides in the blood
Clearing of multi-cellular parasites.
Challenges of muti-cellular parasites:
- Parasites are biologically and chemically more similar to humans
compared to other pathogens
- Less antigenic
- Parasites are big cannot be phagocytosed by macrophages and
neutrophils
IL4 produced by DC --> Th2 cells produce IL4/5 --> instruct B cells for IgE
production --> IgE bind to FcER1 receptor expressed on the surface of
basophils, eosineophils and mast cells they remain inactive --> when FcER1 is
crosslinked because the Fc tail of IgE antibodies recognize their antigen
(parasite or allergen) (depot formation) they start to degranulate --> secretion
