Hypersensitivity 2,3,4 Flashcards Preview

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Flashcards in Hypersensitivity 2,3,4 Deck (18):

def. hypersensitivity

immune mediated tissue injury


6 cause sof hypersens.

1. allergic rxn
2. some infections
3. autoimmune
4. transplant rej.
5. dysregulated activation of immune system
6. unknown etiology


4 classifications of hypersens.

1. IgE mediated
2. mediated by ABs binding to antigens on cell membrane or basement membrane of extracellular matrix
3. immune complex disease
4. delayed-type hypersensitivity and other cell mediated rxns.


what is goodpastures

autoantigen- non-collagenous domain of basement membrane
consequnce - glomerulonephritis, pulm. hemmorage


4 possible mechanisms of problems in type 2

1. opsinization and phag. (macros of NK)
2. complement and Fc receptor mediated inflammation
3. antibody mediated cellular dysfunction - myasthenia gravis
4. antibodies against RBCs cause autoimmune hemolytic anemia


what happens in type 3

antibodies bind to antigen and coause complexes that become deposited in places


when is immune complex disease most likely

in equivalence zone - when only a slight excess of antigen


5 examples of immune complex disease

1. serum sickness
2. hypersensitivtiy vasculitis (drug reaction)
3. systemic lupus
4. persistent infections
5. mould or plant/animal inhalation


2 common problems in type 3

1. vasculitis
2. glomerulonephritis


what is type 4

cell mediated- situations where T-cells mediate response, but not antibodies


what is mech. in type 4

disease is collateral damage
- normal T-cell response to infectiin (TB)
- abnormal response
- autoimmune response
- alllergic response


3 possible functions of effector T-cells

1. Th - exert effects by activating other cells
2. cyto toxic T cells - kill directly
3. produce inflammatory cytokines


3 important considerations in type 4

1. what starts the immune response (t- cell activation)
2. type of effector cell generated
3. regulation of the response - Treg, inhib. molecules


3 adverse effects of persistent inflammation

1. overproduce TGF-beta
2. fibrosis of tissues, loss of normal cells and functions
3. carcinogenic effects


what is importance of TGF-B in cancer

TGF-B can be expressed by cancer cells which turns off immune system


important difference between 2 and 3

both Antibody mediated, but 2 is generallyorgan specific, while 3 is systemic


what happens in contact hypersensitivity (poispn ivey)

when contact allergen, langerhan cell internalizes and expresses on membrane - activaes T-cells that then cause damage


how do superantigens cause attacks

may be produced by bacteria and sudden inflammatory reactions due to over production of cytokines

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