Lecture 23 Flashcards
State the 3 characteristics that usually accompany an acquired immune response that causes and allergy.
(which Ig type)
(which cells types)
(T cell response type and the 3 IL’s it creates)
- presence of allergen-specific IgE
- Mast cells and Eosinophils (being recruited/activated)
- Th2 responses and IL-4, IL-5, and IL 13
State the 2 common mechanistic aspects of allergic diseases
- Results in harmful immune responses
- Noninfectious Ags drive the immune responses
- IgE is generated
State the 2 type of molecules that allergens can be. Which phenotype bias is related to most allergic immune reactions?
Proteins and Glycoproteins
Th2 phenotype
Allergens can activate innate immune responses by which 2 activities?
Intrinsic enzymatic activity
Activation of PRRs (pattern-recognition receptors)
Indoor allergens are usually associated with ____ while outdoor allergens are usually associated with_____ _____.
Asthma
Allergic rhinitis
What characteristic of some allergen helps them to cross skin or mucosal barriers? Why are most allergens contained within particles?
protease activity
Because small particles are aerodynamic and can be spread to mucosa in the nasal/bronchial areas more easily
Atopy leads to ____-mediated allergic inflammation. State the 4 factors that influence the development of atopy.
Th2
- Genetic factors (HLA, FcR1-B, IL-4, CD14 mutations)
- Environmental factors (allergen sensitization, few siblings, excessive hygiene, Antibiotic before age 2)
- Defects in Target organs (compromised epithelium in skin/GI tract)
- Triggers (Viral infections, Pollutants, Exposure to allegens)
State some factors that favor the Th1 phenotype and what favoring this phenotype leads to. Do the same for the Th2 phenotype.
Th1 phenotype: leads to protective immunity Older siblings Day Care exposure TB, Measles, Hepatitis A infection Rural environment
Th2 phenotype: leads to allergic diseases Antibiotic use Diet Sensitization to household allergens Urban environment
What term describes the presence of a type I hypersensitivity reaction to an allergen? What type of test can be conducted to demonstrate whether or not a pt exhibits this term?
Atopy
Skin prick test
State the chances of the following atopic parent combinations producing a child that is atopic
2 atopic parents:
1 atopic parent:
0 atopic parents:
2 atopic parents: 75%
1 atopic parent: 50%
0 atopic parents: 25%
State the 4 genes that are known to be involved with the inheritance pattern of allergic diseases
- The Beta chain of the receptor for IgE (FcSigmaRIbeta)
- IL-4 gene
- HLA-DR alleles
- CD14 gene
Describe how a polymorphism on the CD14 gene can affect the allergic tendency of a person.
CD14 is a PART of the receptor for bacterial cell wall LPS (lipopolysaccharides)
Different polymorphisms of CD14 could trigger an exaggerated immune response to an LPS molecule that is not actually harmful
What percentage of Allergic development comes from genetics and what percentage comes from the environment?
Genetics: 20%
Environment: 80%
True or False:
The month you are born in can affect your tendency to develop an allergy. explain.
True
ex. children born during the months of birch pollen release are much more likely to develop a birch pollen allergy due to “allergen sensitization” occuring
State another name for the “hygiene hypothesis”. State the 2 mechanisms that the hygiene hypothesis attributes the to increasing incidence of allergic diseases
Hygiene hypothesis aka germless theory
- Shift in immune system phenotype toward Th2 type responses
- Decrease in T reg cells that would usually calm the exaggerated allergic immune reactions
What is the Main postulate of the hygiene hypothesis? explain this postulate in terms of Th1 and Th2 phenotypes
Main postulate: increased incidence of allergy is associated with the decrease in exposure to common infections during early life
Basically, infections in early childhood stimulate Th1 type responses and shift the immune phenotype balance from Th2 (favored during neonate age) toward Th1
What is BCG and how is it related to allergic reactions?
BCG is a bacterial strain that has been shown to cause the proliferation of T regulatory cells
Early studies of BCG vaccination have shown that they can decrease the severity or eliminate allergic reactions in most people.
All of the following are type I hypersensitivity reactions with IgE as effectors. State the 2 effector cells that IgE can be found on in the following conditions.
Anaphylaxis:
Asthma and Hayfever:
Food Allergy:
Anaphylaxis: IgE on basophils and mast cells
Asthma and Hayfever: IgE on Mast cells and Th2 cells
Food Allergy: IgE on Mast cells and Th2 cells
For Mast cells, state the following.
Site of Maturation: Does the cell circulate? Are it's mature cells recruited into tissues? Do it's mature cells reside in CT? Can it's mature cells proliferate?
Mast Cells
Site of Maturation: CT Does the cell circulate? No Are it's mature cells recruited into tissues? No Do it's mature cells reside in CT? Yes Can it's mature cells proliferate? Yes
For Basophils, state the following.
Site of Maturation: Does the cell circulate? Are it's mature cells recruited into tissues? Do it's mature cells reside in CT? Can it's mature cells proliferate?
Basophils
Site of Maturation: Bone Marrow
Does the cell circulate? Yes (0.5% of blood leukocytes)
Are it’s mature cells recruited into tissues? Yes
Do it’s mature cells reside in CT? No
Can it’s mature cells proliferate? No