Hypersensitivity Flashcards
Which hypersensitivities can lead to tissue damage?
Hypersensitivity 2 and 4
Which hypersensitivities are mediated by antibodies?
Hypersensitivity 2 and 3
Which hypersensitivity is responsible for ALLERGIC reaction?
Hypersensitivity 1
Which hypersensitivity is involves T cell mediated DTH?
Hypersensitivity 4
What is the mechanism of hypersensitivity 1?
- Th2 cells with cytokine IL-4
- trigger class switch in B cells
- IgE circulating binds FceR1 on MAST Cells and leads to activation of mast cell
- cross linking signal increases mast cell degranulation
- mediators increase inflammation
What receptor is important for Hypersenstivity 1 ? Which Antibody is involved ?
FceR1 receptor , IgE
What is immediate phase of H-Sensitivity 1 ?
increase in edema , vasodilationm, sm muscle contraction
What is latent phase of H-Sensitivity 1 ?
2-24 hours later … increase in leukocytes to the area (neutrophils, eusinophils and macrophages
What are the clinical syndromes of H-Sensitivity 1 ?
- asthma- increased capillary permeability in lungs , SOB
2. anaphylaxis - bronchi sm muscle vasodilation , decrease in BP
What can we use to detect Type 1?
Allergen testing
What is Hypersensitivity 2?
IgM and IgG against surface (cell surface or extracellular matrix
What are the mechanisms of Hypersensitivity 2? (2 main)
- Complement-mediated (cytotoxic)
• Opsonization ( increase in C3a / C5a or recruitment and activation of inflammatory cells )
- ENHANCES Phagocytosis (via FcRy / CR1 receptors)
2.Non-cytotoxic
• Change in physiologic behavior of a cell
Examples of Non-cytoxic effects of hypersensitivity 2?
- GRAVES disease
2. Myasthenia gravis
Graves disease?
- type of sensitivity?
- mechanism?
- sxs
- Type 2
- Ab binds TSH receptor stimulating TSh release without hormone (non cytotoxic)
- hyperthyroidism
Myasthenia Gravis
- type of sensitivity?
- mechanism?
- sxs
- Type 2
- Ab inhibits Acetycholine binding Ach receptor (non -cytotoxic)
- muscle weakness