Hypersensitivities Flashcards
Which type of immune response is immediate and associated with allergies?
Type I
Which type of immune response is immune complex mediated?
Type III
Which type of immune response is T cell-mediated (example = poison ivy)?
Type IV
Which type of immune response is antibody mediated?
Technically Types I-III, but specifically Type II
Which antibody is associated with Type I hypersensitivity?
IgE
Which antibody is associated with Type II hypersensitivity?
IgM and/or IgG
Which antibody is associated with Type III hypersensitivity?
Usually IgM and/or IgG
Which antibody is associated with Type IV hypersensitivity?
NONE :)
What cells are associated with Type IV hypersensitivity?
T cells
What thing do all forms of hypersensitivity require?
Prior exposure to the antigen
What is the result of prolonged or repeated exposure to an antigen?
Tissue damage
How is the immune response to the antigen unique in hypersensitivity reactions?
Excessive or inappropriate
What kinds of antigens can be targeted by hypersensitivity reactions?
Both self antigens or foreign antigens
What results from a hypersensitivity reaction targeting self antigens?
Autoimmune disease
Type I hypersensitivites occur within what kind of time frame after antigen exposure?
Within minutes or hours
What is usually the term for the antigens involved in Type I hypersensitivities?
Allergens
About what percentage of the population suffers from Type I hypersensitivity reactions?
54%
What are the chain of events of an allergic reaction?
1 allergen enters body 2 APC eats it 3 APC presents peptides on MHC II 4 helper T cells are activated 5 helper T cells activate B cells (plasma cells) specific to antigen 6 B cells make IgE
The activated helper T cells in an allergic response differentiate into which bias subtype?
Th2 (strong response)
What cytokines cause the antibody class switching to IgE?
IL-4 and IL-13
How long do IgE antibodies live in the blood?
About a day
In what circumstance do IgE antibodies have a half life of several weeks?
When attached to mast cells
Why is it common for a person to not have an initial allergic reaction to the first exposure of an antigen?
Takes a while for IgE antibodies to accumulate and load onto mast cells
What specific part of the IgE antibodies have a high binding affinity to mast cells?
Fc regions
Where are mast cells found in the body?
Everywhere
Which exposure to an allergen will activate mast cells?
Second
What is the result of multiple allergens binding to IgE antibodies on mast cells (clustering)?
Mast cell degranulation and release of “chemistry”
What is included in the immediate early phase of chemistry released by mast cells during an allergic reaction?
Vasoactive amines (ex. = histamine), proteases, prostaglandins
What is included in the late phase of chemistry released by mast cells (6-24 hours)?
IL-4 and TNF pull in other WBCs like neutrophils and eosinophils
What is the order in which these cells respond to an allergic reaction: basophils, mast cells, eosinophils?
1 mast cells (immediate response) 2 basophils (rapid response) 3 eosinophils (delayed response)
Where do basophils come from during an allergic response?
Brought into tissue from blood by signals sent by mast cells
Where do eosinophils come from during an allergic response?
Recruited from bone marrow (T helper secreting IL-5)
Which cell type plays a prominent player in chronic allergic reactions: mast cells, basophils, eosinophils?
Eosinophils
Which cells involved in an allergic response exhibit degranulation?
Mast cells and basophils
Which cells involved in an allergic response have receptors for IgE?
Mast cells and basophils
What is the term for allergic people?
Atopic individuals