Innate immunity: ILCs and NK cells + Review Flashcards
What are nk cells
Innate lymphoid cells = ilcs
What do nk cells share
Progenitor = common lymphoid progenitor with b and T cells
But nk cells = innate immune cells, but b and T cells = adaptive
Nk cell = most abundant ilc
Describe ilcs and nk cells
Derived from common lymphoid progenitor
Not antigen specific = provide innnate immunity, not specific to epitope
How many types of ilcs
3
What determines what ilc generates into
Cytokines can influence which ilc to generate into
Which cell the precursor differentiates into
Describe ilcs - reside
Tend to reside in tissues = important in mucosal immunity, fight against pathogens
Describe ilcs - contribute
To defuse against specific microbes
Describe ilcs - research
Very active area of research
Where are nk cells found
In tissues or circulation
What leads to differentiation into diff ilcs
Diff inducing cytokines lead to differentiation into diff ilcs = secrete diff cytokines
All ilcs are produced in same amount in response to all infection?
May need more of one type of ilc = depnds on infection
What does ilc1 do
Induce differentiation into ilc12, and produce fin-gamma = effector molecule
Mostly = defense against viruses, intracellular pathogens
What does ilc2 do
Expulsion of extracellular parasites
What does ilc3 do
Immunity to extracellualr bacteria and fungi
What cells have prrs
Nk, t, b, all myeloid
But ilcs = group 1,2,3 = do not have prrs
Describe innate lymphoid cells- take home
Act in tissues
Activated by cytokines produced by dendritic cells or other cells (epithelial cells)
Secrete cytokines that contribute to Pathogen killing
Describe innate lymphoid cells- pic
Gut mucosa
Activated dendritic cell produce cytokine, that activates ilc = clear intracellualr pathogen
Epithelial cells secrete cytokiens then activate ilc2 - then more cytokiens —> goblet cells clear parasitic infection
Paneth cells clear extracellalr bacteria and fungi
Are all ilc cells tissue resident
Nooo
Ilc2 can circulate
Describe research data - ilcs
Immunofluroescent staining of mouse ilea = part of gut
Mice untreated = control
Mice treated = with il-25 = cytokien produced during helminth parasitic infection
= more ilc cells and some in lymphatic vesssels = ilcs circulate
What are conclusions of research of ilcs
New knowledge constantly changes understanding of immune system
Ilc2 = not solely tissue resident = can travel in some cases
What are nk cells
Lymphoid cells with innate immune functions
What do nk cells express
Receptors for self proteins that can be induced by infections, malignant transformations (cancer tumours) and other stresses
What can activated nk cells do
Kill altered self cell (directly kill host cells)—> due to infection or tumour cells
Produce cytokines that induce adaptive responses against the altered self cell, help differentiation of T cells
Describe nk cell receptors - gen
Germaine encoded = do not change,innate immune cells = receptors the same
Have 2 receptors = activating and inhibitory receptors
What do nk cell receptors recognize
Mhc class one molecules or mhc class 1 like molecules
Mhc class one molecules expressed on all nucleated cells = all host cells can express this
What does nk cell have to do
Interpret variety of signals, determine if kill cell or not
Describe nk cell = normal context
Nk cell receives activating and inhibitory signal = inhibitory signal prevents activation of nk cell
Mhc class 1 binds inhibitory receptor, activating ligand binds activating receptor on nk cell, self proteins expressed on cel surface
If have both receptors = inhibitory wins = do not kill cell
Describe nk cell = disease context 1 - gen
Altered self cell does not trigger inhibitor receptor = nk cell receives only activating signal = nk cell kills target cells via granules that trigger apoptosis, creates holes/pores in target cells = leads to cell death
Describe nk cell = disease context 1- pic
Virus prevents cell from presenting peptide on Mhc class 1 or conformation diff
No inhibitory signal
= only positive signals so kills cell
Describe nk cell = balance, another way
Details unclear but overall balance of signalling by these receptors determines whether an nk cell kills target cell
Balance = if more activating = kill, if both = normal, if missing self = kill
Describe nk cell = disease context 2- gen
Nk cell can trigger apoptosis in target cells that express a specific reactor = dr4/dr4 that bind to trail on nk cells = target dies by apoptosis triggered by signalling from this receptor binding
Describe nk cell = disease context 2- pic
Activated nk cells express trail = death receptor
Dr4/dr5 expressed, some v stressed cells express ligand for trail
Once bound = nk cells start intracellular signalling and caspase 8 activated = programmed cell death, target cell programs own cell death (not Like cell death from granules)
What can nk cells do
Directly kill infected cells
