Final: Hypersensitivity Flashcards
What is Type I hypersensitivity mediated by?
IgE and mediators secreted from mast cells (binds to CD23)
- histamine: dilation of small vessels
- proteases: local tissue damage
- prostaglandins: vascular dilation
- leukotrienes: stimulate smooth muscle contraction
- cytokines: local inflammation in late phase
What is Type II hypersensitivity mediated by?
Abs that bind tissue antigens and cause complement dependent tissue injury
What is Type III hypersensitivity mediated by?
Circulating Ag-Ab complexes which deposit in vessels and cause complement-dependent injury in blood vessel wall
- antigens must be soluble
- can cause edema
What is Type IV hypersensitivity mediated by?
Mediated by T cells and inflammation
- Cytokines from Th1 and Th17
- Macrophages
- Cytotoxic T Cells
What T helper cell is involved in Type I hypersensitivity?
Th2 cells and IL-4
What is the late phase in Type I hypersensitivity characterized by?
Eosinophils
Neutrophils
T cells
What is Allergen Specific Immunotherapy?
Induce peripheral T cell tolerance
Increase threshold for mast cell and basophil activation
Decrease IgE-mediated histamine release
Generation of induced regulatory FoxP3 CD4 CD25 Treg cells
What is Type II Hypersensitivity?
Specific antibodies that interact to specific tissues or cells
-activates complement system or NK cells
What are examples of Type II hypersensitivity?
ABO Blood Transfusion Graves Disease Myasthenia Gravis Hemolytic Disease of Newborn Drug Induced Hemolytic Anemia
What are examples of Type III hypersensitivity?
Lupus
Arthus reaction
Serum sickness
What are examples of Type IV hypersensitivity?
Multiple Sclerosis Rheumatoid arthritis Type I diabetes Crohn's Disease Poison Ivy Tb
