Type II, III, IV Hypersensitivity Flashcards
1
Q
type II cytotoxic hypersensitivity
A
- faulty self-reactive B cells produce IgG and IgM Ab that attack exogenous AND endogenous Ags
- IgG and IgE mediated
2
Q
cytotoxic
A
toxic to cells
3
Q
endogenous Ags
A
self antigens (present on cell membranes)
4
Q
exogenous Ags
A
from bacteria (absorbed on membrane surface), anything outside the body
5
Q
Ab binds to Ag and form IC –> Ag bearing cell (IC) destroyed via…
A
- complement
- inflm
- phagocytosis
6
Q
type III immune complex hypersensitivity
A
- Ab bind to free-floating Ags –> form IC that is deposited in tissue
- IC too small & insoluble so cannot be destroyed
- IC circulates in blood until deposited –> activates complement system –> inflm & tissue damage
7
Q
type IV T-cell mediated hypersensitivity
A
- Ag (bacteria) enters cell and engulfed by dendritic cell
- macrophage presents Ag to T-cells = T-cells sensitized
- Cytotoxic T-cells attack macrophages holding foreign Ags –> death of own cells –> inflm and tissue damage
8
Q
types of type IV hypersensitivity
A
- direct
- delayed
9
Q
direct type IV
A
- T-cells attack any cell with that Ag (immediate rxn)
10
Q
delayed type IV
A
- pre-sensitized T helper cells release cell-damaging lymphokines (mediators produced by T cells)
11
Q
type IV hypersensitivity examples
A
- intradermal injection of TB
- contact dermatitis
