Hypersensitivity Flashcards
Classifications of immune hypersensitivity and the molecule responsible for each
I Immediate hypersensitivity - IgE, II Cytotoxic reactions - IgG or IgM and complement, III Immune complex rxns - IgG or IgM and complement, IV delayed type - T-cells and macrophages/PMNS
Categories of Type I (IgE mediated) allergic hypersensitivity
Atopic (inherited) and Non-Atopic (non-inherited)
Two main methods by which Th2 cells stimulate mast cells to degranulate
Releasing IL-4 to stimulate B-cells to release IgE, which coats mast cells, and releasing Histamine-releasing factors which can directly activate mast cells
Are mast cells free floating or tissue fixed and where do they tend to be clustered?
Tissue-fixed. Clustered around cell surfaces and postcapillary venules
What two cytokines can overstimulate IgE production, leading to excessive mast cell degranulation?
IL-4 and IL-5 (released from Th2 cells)
Hygeine hypothesis says that clean environments are downregulating our expression of what?
Treg cells (which help prevent allergic reactions)
Examples of Type II allergic reactions
Hemolytic disease in newborns (Rh antigen disease), drug induced hemolytic anemia, Goodpasture syndrome (anti-basement membrane antibody disease)
How can hyperthyroidism be caused by a Type II allergic reaction?
An antibody against the TSH receptor can be created which binds to TSH receptor and overactives cell
Treatment for Type II and Type III allergic reactions
Glucocorticoids, cytoreductive therapy (immunosuppression, eg goodpasture), plasmapheresis (deplete antibody titer)
Examples of Type III allergic reactions
Serum sickness, post-strep glomerulonephritis, systemic lupus erythematosus (nuclear antigens), polyarteritis nodosa (Hep B antigen)
At the height of a Type III allergic reaction is the level of C3 complement decreased, not changed, or increased?
Decrease (C3 is being consumed by the overactivation of complement)
Which hypersensitivity reaction is independent of antibody?
Type IV Hypersensitivity
Name some Type IV allergic reactions
Contact dermatitis (poison ivy, jewelry, etc), Tb, Hypersensitivity pneumonitis, sarcoidosis perhaps, autoimmunity perhaps
What receptor on mast cells and basophils binds IgE?
FceR1
What type of allergic reaction is diagnosed with skin testing?
Type I hypersensitivity. Also diagnosed with in vitro RAST testing to detect IgE
