Hypersensitivity Reaction Leacture Flashcards
Disorders of the immune system include?
Hypersensitivity reactions Autoimmune diseases (caused by immune rxns against itself) Immunologic deficiency syndromes (results from defects in normal immune responses)
What does checks and balances in the immune system?
Inadequate control or inappropriately targeted
What are some causes of hypersensitivity reactions?
Autoimmunity Rxns against microbes Rxns against environmental antigens Inappropriate control Impossible to eliminate antigen Positive feedback loops --> chronic inflammation
What is type I Hypersensitivity?
Allergy/Atopic disorders Rapid Production of IgE antibody Strong TH2 responses Release of mediators from mast cells Can be fatal --> anaphylaxis
How are mast cells activated?
Exposure to allergen –> activation of TH2 and IgE class switching in B cells –> IgE production –> binding of IgE to mast cells –> repeat exposure to the allergen –> activation
What happens when cytokines are produced after mast cells are activated?
Late phase reaction
What happens when vasoactive amines or lipid mediators are produced after mast cells are activated?
Immediate hypersensitivity reaction
What is a late phase reaction?
Leukocyte infiltration
Epithelial damage
Bronchospasm
What is a immediate reaction?
Vasodilation
Vascular leakage
Smooth muscle spasm
Why does type I hypersensitivity occur?
Reaction dependent on TH2 and IgE primarily meant for combating parasitic infections
Helminthic infections –> IgE production/Mast cells/eosinophils
Type II Hypersensitivity is what?
Antibody Mediated Diseases
Opsonization & phagocytosis
Inflammation
Antibody mediated cellular dysfunction
What’s an example of opsonization and phagocytosis?
Autoimmune hemolytic anemia
What’s an example of inflammation?
Goodpasture syndrome
What are some antibody mediated cellular dysfunction?
Myasthenia Gravis
Graves Disease
Type II Hypersensitivity is what?
Immune Complex Diseases
Antigen-Antibody Immune complexes
Exogenous or endogenous antigens
Size of complex is a critical determinatn
Deposit in blood vessels or in regions where blodd in filtered with high hemodynamic pressure
Inflammation
What is acute serum sickness?
Foreign serum administered for passive immunization
Type IV Hypersensitivity is what?
T Cell Mediated CD4 T cells --> cytokine mediate inflammation Delayed type hypersensitivity Macrophage mediated tissue damage Granulomatous inflammation CD8 T cells --> direct cell toxitiy Type I diabetes mellitus
Formation of granulomas occurs how?
APC binds an antigen and IL2 works on the CD4 TH1 cell
TNF goes to the creation of monocytes which are acted on by IFN-gamma
TH17 causes what?
Inflammation and tissue injury
TH1 causes what?
Macrophage activation and inflammation
