9 – Innate Immunity VI (ILCs & NK cells) Flashcards
NK cells:
Derived from common lymphoid progenitor
Not antigen specific – provide innate immunity
how many types of ILC is there
3
cytokines can influence…
what kind of ILC to geenrate into
ILCs are found…
Tend to reside in tissues - important in mucosal immunity
ILC contribute to…
-Contribute to defense against specific pathogens
-Might need many types of ILC to fight
ILC activated by:
by cytokines produced by DCs/other cells (epithelial cells)
ILCs secretes
Secrete cytokines – for pathogen killing
NK cells found in…
can be found in tissues/in circulation
NK cells can…
directly kill cells
Different inducing cytokines – lead to
differentiation into different ILCs – secretes different cytokines
ILC 2 - is special, why
some can circulates
-Some found in lymphatic vessel
NK cells are…
ILCs (innate lymphoid cells) with innate immune functions
Nk cells Express receptors for self-proteins induced by: (3)
-Infections
-Cancer – malignant transformations
-Other stresses
NK cell receptors are … encoded
-Germline encoded – don’t change
-Can belong to same structural family
-NK cell – interpret variety of signals
Activated NK cells can: (2)
-Kill altered self-cell – due to infection/tumor cells
-Produce cytokines – induce adaptive responses against altered self-cell
2 types of NK cell receptor:
Activating receptors & inhibitory receptors
Nk cell receptors recognize & binds to
-Recognize MHC class I molecules / MHC class I-like molecules
MHC I molecules are expressed on….
all nucleated cells
NK cells in normal context
-NK cell receives activating & inhibitory signal
-Inhibitory signals prevent activation of NK cells
-NK cells don’t kill normal cell
NK cells in disease context:
-Altered self-cell doesnt trigger inhibitory receptor
-NK cell only receives activation signal
-NK cell kills target cells via granules (create holes/pores) triggering apoptosis
OR
-Nk cell can trigger apoptosis on target cell that express specific receptors* binding to TRAIL on NK cells
*DR4/DR5 - activate caspase 8
-Target cell dies by apoptosis triggered by signaling from this receptor binding
Intracellular signaling –> caspase 8 activated –> target cell programs its own cell death
Nk cell inhibitory receptor bind to
MHC class I
NK cell activation receptor bind to
NK-cell activating ligand
what determines if NK cells kill target cells.
The overall balance of signaling by these receptors
inhibotory > activation
but if theres more activation, it will be activated even if a little inhibitory is present
