IgE Immunity Flashcards
What is Type I Hypersensitivity?
Allergic reactions mediated by IgE
What is Type II Hypersensitivity?
Ab directed against tissue Ag mediated by IgG
What is Type III Hypersensitivity?
Immune complex mediated disease caused by Ag-IgG complexes
What is Type IV Hypersensitivity?
Delayed hypersensitivity mediated by T cells
What is allergy?
It is a disease induced by reaction to a usually innocuous antigen
What is atropy?
It is a genetic predisposition to develop IgE antibodies upon exposure to environmental allergens
What are the major cell mediators of allergy?
Basophils
Mast Cells
Eosinophils
What do mast cells and basophils bind to?
Have high affinity for Fc epsilon receptors
Can the FcR epsilon be occupied by Ab without Ag?
Yes. It is the only FcR that can do that.
What is the main thing required for an allergic reaction?
Need to have had previous exposure to have
an allergic reaction
What are the important cytokines in an allergic reaction?
IL3,4,5,13, and 10.
Especially IL-13 though.
How does the Type I Hypersensitivity occur?
- Contact with allergen and uptake by a DC via an allergic TLR
- DC produces IL-4 instead of IL-12 and present allergen as an immunodominant peptide in MHC II
- IgE response occurs
How does an immunodominant peptide cause an IgE reaction?
Immunodominant peptides are preferentially presented in D MHC II which promotes IgE over IgG
What are the dominant cytokines in an IgE response?
IL-4 and IL-13
How does promotion of IgE class switch occur?
It occurs via CD23 up regulation which leads to IL-4 and IL-23 up regulation
What “arms” the mast cells?
IgE binding to them
What happens to armed mast cells upon subsequent exposure?
They will have the IgE crosslink and linked FcR epsilon will aggregate leading to a singal transduction.
What does the signal transduction that occurs in mast cells with cross linking of IgE trigger?
Degranulation to release the vasoactive inflammatory mediators like prostaglandin and leukotriene
What is the RAST Assay?
Radioallergosorbent Test.
Radiolabeled Anti-IgE will bind to the Ab-Ag complex of the IgE to determine the substances that someone is allergic to.
What is allergen immunotherapy?
Done through shots or sublingually to redirect the immune response
What is Anti-IgE therapy?
Ab used that binds to IgE to suppress IgE mediated symptoms
