11: Hypersensitivity Flashcards
What is hypersensitivity?
Immune response causing collateral damage
Allergic and autoimmune responses are example of what?
Hypersensitivity
What mediates Type I hypersensitivity reactions?
Antibodies (IgE)
type iv
time frames
Allergy involves reactions to ___ substances.
harmless
What name is given to harmless substances which cause allergic reactions?
Allergens
Type I reactions tend to occur ___.
immediately
Type I allergies tend to be (immediate / delayed) and (consistent / unpredictable).
immediate
consistent
Name an antigen-presenting cell which involved in Type I allergic responses.
Dendritic cells
Mast cells
Which cells produce the antibodies responsible for mediating Type I hypersensitivity reactions?
B cells
(also memory B cells)
What is urticaria?
Hives
i.e big red lumpy rashes
How long does urticaria typically last?
2-6 hours
angioedema
How can a Type I allergy be diagnosed?
Serum IgE test
Skin prick / patch testing
Challenge testing
serum tryptase
epipen doses
What is the jist of Type IV hypersensitivity reactions?
Delayed response
What mediates Type IV hypersensitivity reactions?
T cells
Name an example of Type IV hypersensitivity reactions.
Allergic contact dermatitis
How long after exposure to allergens do Type IV hypersensitivity reactions start?
24 - 48 hours
Give an example of a substance which causes a Type IV hypersensitivity reaction.
Nickel
Poison ivy
Thiuram (used in rubber gloves)
Colophany used in adhesives
Deodorant chemicals
garlic
stuff in tattoos
How can Type IV hypersensitivity be diagnosed?
Patch testing
Nappy rash and excessive handwashing are examples of which type of dermatitis?
Irritant contact dermatitis
Is irritant contact dermatitis an example of hypersensitivity?
No
not an immune response
atopic eczema
Dermatitis can be caused by allergens, irritants or ___.
infection e.g fungal
