Hypersensitivity Flashcards
What are the components of a type I reaction?
- IgE, allergen specific
- Mast Cells
- Allergen
- Eosinophils
- CD4+ Th2 cell
What cytokine is responsible for class switching of a B cell to produce IgE?
IL-4
How are mast cells and basophils activated?
Cross linking antigen via Fc receptors.
What are the biologic effects of mast cell mediators (6)?
- Vasodilation
- Vascular leak
- Bronchoconstriction
- Intestingal hypermotility
- Inflammation
- Tissue damage
What is responsible for the late phase reaction in a type I hypersensitivity?
IL-5 from mast cells ant Th2 cells recruit and activate eosinophils which release additional mediators.
What are 4 clinical syndromes associated with type I hypersensitivity?
- Allergic rhinitis, sinusitis
- Food allergies
- Bronchial asthma
- Anaphylaxis
What antibodies are involved in a type II hypersensitivity?
IgG or IgM
What diseases are associated with type II hypersensitivity (5)?
-Transfusion reaction
-Hemolytic disease of the newborn
-Autoimmune hemolytic anemia
-Goodpasture’s disease
Pemphigus vulgaris
What does the direct Coombs test detect?
Antibodies directly on the surface of the RBC.
What does the direct Coombs test help diagnose?
- Hemolytic disease of the newborn
- Autoimmune hemolytic anemia
- Transfusion reaction
What does the indirect Coombs test measure?
Anti-RBC antibodies in the serum.
What is the indirect Coombs test mainly used for?
- Cross-matching
- Blood typing
- Antibody detection
- Antibody identification
What are the clinical symptoms of a transfusion reaction?
- Fever
- Low BP
- Nausea and vomiting
- Back and chest pain
How does hemolytic disease of the newborn occur?
Occurs in a second pregnancy of a woman who is Rh - and has a Rh + baby.
What is the mechanism of pemphigus vulgaris?
Antibody-mediated activation of proteases, disruption of intercellular adhesions.
