Lecture 10/11 Flashcards
What receptors do ancestral T cells have?
- Gamma delta
- Modern have alpha beta
What type of antigens did ancestral T cells recognize?
Lipid rich
Where are primitive T cells important?
- Host environment interface
- Gut, lungs, skin, etc
What cytokines do ancestral T cells secrete?
Inflammatory cytokines
IL6
IL7
IL 17
What is the CD3/4 T cell?
Helper T cell
What is Th?
Helper T cell
What is orchestrator of adaptive response?
T cell
What are T lymphocytes required for?
Cell mediated immunity
Antibody immunity by B cells
What regulates T cell repsonse?
Treg
Cytokines
What do antibodies recognize?
3d form of antigen?
What do T cells recognize?
Antigens in context of self MHC
What happens when APC presents antigen to naive T cell??
One of the following will develop: TH1 TH2 TH17 Treg
What does subset commitment depend on?
Host genetics
Infection type
TLR profile
Cytokine profile
What does Th1 do?
Enhances and amplifies cellular mediated immunity by activating macs or CD8s
What does TH2 do?
Promotes antibody production
What does Treg do?
Modulates or supresses immune response
What does TH17 do?
Promotes chronic inflamatoin
What does T follicular do?
Promotes optimal antibody formation in germinal centers
Another name for TH1?
TMMI - Tcell mediated Macrophage immunity
What is TMMI?
TH1 direction
Tcell mediated Macrophage immunity
What cytokine initiates TMMI?
IL 12
What does IL12 do?
Initiate TMMI
What type of infection causes TMMI?
Uptake of complex antigen by DC
TMMI MHC?
MHCII
What triggers DC maturation?
Uptake of pathogen or its complex antigens
What does mature CD do?
- Moves to lymph
- Down regulates phagocytosis
- Upregulates MHCII presentation
- IL 12/18 upregulatinoin
What does IL 18 do?
Leads to TMMI
Amplifies IL12 properties
Critical cytokine for Th1?
IL12
How do we identify Th1 resposne?
TF: T-BET
What does Tbet signify?
Th1
What does Th1 upregulate in presence of its antigen and ILs?
CD28 & 40L
What costimulatory signal necessary for T & Bcell mediated repsonse?
CD40/40L
CD28/B7
What does commited TH1 produce?
INFgamma
What does commited TH1 produce?
INFgamma
What can produce INFgamma?
TH1
NK
CD8
What is pivotal step for amplifying T cell mediated mac activation?
INFgamma
What does INFgamma do?
- Pivotal step for amplifying T cell mediated mac activation
- Signature cytokine of ongoing TH1
- Attracts effector cells to area
- Controls MHC display by APCs
- Stimulates killer cells
- Increases proinflamatory molecules
What do activated Th1s do?
Upregulate IL2 production and IL2 receptors
What does IL2 do?
Critical growth cytokine in Th1 supporting rapid proliferation stimulated T cells
Where do IL12/18 come from?
DC
Where does IL2 come from?
Activated TH1s
What does INFgamma down regulate?
Th2
Th17
What is IL21?
- Potent activator of CD8
- Activated Th1 releases
What releases IL21?
Activated TH1
Where does TH1 activation usually occur?
Lymph node or spleen
What are the proinflammatory cytokines?
IL1
IL6
IL8
TNF alpha
What produces proinflamatory cytokines?
Activated macrophages
Which cytokines can elevate body temp?
IL1 in concert with IL6
What cytokines facilitates T cell responsiveness to IL2?
IL1
Agonist of IL1?
IL1-Ra
How doe IL 6 differ from IL1?
Growth and differentiation effect on B cells
Effects Bone Ca resorption
Which inflamatory IL is a chemokine?
IL8
What does IL 8 do?
Major stimulus for proliferation, mobilization and recruitment of neurophils
What IL is main inducer or neutrophils?
IL8
What IL is main inducer or neutrophils?
IL8
What produces IL8?
Macs
Neuts
Many others
What is delayed hypersensitivity?
TMMI
What is positive TB skin test example of?
TMMI
How does quantiferon gold work?
- Lymphocutes from blood incubated with TB antigens
- If patient has had TB, INFgamma is released
Do NK cells have CD3?
No
How does INFgamma relate to NK?
Produces and highly effected by
Are NKs antigen specific?
No, no MHC
Most important role of NK?
Frontline defense while adaptive ramps up
How can NK activity be repressed?
- KIR - Killer cell inhibitory receptor
- Found on surface
- Respond to self MHC
How does KIR work?
In absence of self MHC, KIR will be turned off only if target cell has NK activating receptor
How can NK cells kill?
Direct cytotoxicity
Can mediate antidbody dependent killing via Fc receptor that recognize antibody bound antigen
What can CD8s do?
Directly kill foreign, infected, or mutated cells
What do CD8s defend against?
Virus & tumor
What is different betweeen what NK and CD8 recognize?
CD8 recognizes antigen in MHC
NK recognizes altered MHC1
Critical CD8 constimulatory signal?
Produced by NK cells in area:
INF gamma
IL2
Most important influence of CD8 development?
- Concurrent CD4 development
- Activated Th produce IL2 and INF gamma
What does HIV virus do?
Destroy CD4 cells
What does IL21 do?
Potent proliferative stimulus to CD8
Do CD8 cells need costimulation once activated?
- No
- Makes sense as most infected cell are somatic and do not have B7
How do APCs recognize virus?
- TLR, display in MHCII
- Also displays some in MHCI which will lead to its death
Can most APCs be infected by virus?
No but they will display some antigen in MHC i to prime CD8 whiich will funfortunately lead to their death
4 ways CD8 can be activated?
- INFgamma from NK
- 40/40L, CD28/B7 presentation by APC
- CD4 IL2/21 activation
- MHC I /II cross presentation by APC
First step in CD8?
NK reacting to altered MHCI or CD8 recognition of MHCI with antigen
Killing steps of CD8/NK?
- Pore formation vira perforin making cell osmotically unstable
- Injection of granzymes
- Can also induce apoptosis
How do NK/CD8 induce apoptosis?
Fas/FASL system or CASPASE
What are Fas/FASL system or CASPASE?
How NK and CD8 induce apoptosis
What turns off cytotoxicity?
- Elimination of target
- In absence of target cell will kill itself via FAS/FASL
What turns off cytotoxicity?
- Elimination of target
- In absence of target cell will kill itself via FAS/FASL
- 10% will remain as memory cells
What does IL4 cause?/
THO - CD4TH2
What signifies TH2?
GATA-3 TF
What does GATA3 TG signify
TH2
What produces IL4?
- DCs
- Committed TH2
What type of infection activates TH2?
Extracellular antigen
What type of infection activates TH1?
Intracellular
What can stimulate TH2 movement?
IL4 from DC
IL4 from TH2
B cell antigen presentation
What does IL4 inhibit?
Th1
Th17
What type of response does IL4 drive
B cell growth
What is the major source of IL4
TH2 cell
What does TH2 produce other than IL4
- IL21, 5, 6, 10
- Promote B cell growth and antigen switching
What promotes B cell growth and antigen switching?
- IL21, 5, 6, 10
What does IL21, 5, 6, 10 do?
Promotes B cell growth and antigen switching
When is IL21 most effective?
Presence of IL4
Absence of INF gamma
When is IL21 most effective?
Presence of IL4
Absence of INF gamma
What is required for IgE reponse?
IL4 & IL13 & allergy promoting genes
Function of TH2 response?
Enhance B cell function and antibody production
What activates TH17
IL 23
TGF beta
IL6
What does IL23 activate?
TH17
Th17 TF?
ROR
What is ROR
Th17 TF
What is TGF beta?
IL for Treg
What activates Treg?
TGFbeta
What activates TH17?
Extracellular bacteria fungi
What does TH17 produce?
IL17
What produces IL17?
Th17
What does IL17 do?
Recruits neuts
Is IL4, IL 23, or INFgamma dominant?
INFgamma and IL4 strongly suprress Th17
What does mature CD do?
- Moves to lymph
- Down regulates phagocytosis
- Upregulates MHCII presentation
- IL 12/18 upregulatinoin
Is IL4, IL 23, or INFgamma dominant?
INFgamma and IL4 strongly suprress Th17
TF for Treg?
FoxP3
What is FoxP3 do?
TF for treg
Where can Tregs be created?
- Thymus with help of AIRE
2. Periphery with help of IL10 and TGFbeta
What CDs are Treg?
4/25
What are Tregs dependent on for survival and proliferation?
IL2
What does TCR reaction with peptide in MHCI promote?
Activation of CD8
What does TCR reaction with peptide in MHCI promote?
Activation of CD8
What do TLRs do?
TLR instruct antigen presenting cells to set up cytokine profile appropriate to infection
What does TFH do ?
T-FH - promotes optimal high affinity antibody production in germinal center of lymph node
“T follicular helper”
What makes up CD4 family?
HO, TH1, TH2, TH17, Treg, and THFH
What does TH1 encourage along with macs?
CD8
What does trigger for TMMI always involve?
The trigger for a TMMI always involves a TLR on a dendritic cell (DC)
What response need, and require TH2
- TH1 & 2 both like IL2 as it helps them grow, however, survival is not dependent on it
- Treg cells ABSOLUTELY need IL2 for survival
What cytokine is used for host response to stress?
IL1
Difference between IL1 & 6?
IL 6 shows strong growth and differentiation effects on B cells in presence of other by cytokines
What is known as THE proinflammatory cytokine?
TNF alpha
What is angiogenesis?
Making more blood vessels to make inflammation even more potent by allowing delivery of more cells to site of inflammation
Can be caused by TNF alpha
What is angiogenesis?
Making more blood vessels to make inflammation even more potent by allowing delivery of more cells to site of inflammation
Can be caused by TNF alpha
What can cause angioneogenesis?
TNF Alpha
What is most effective at recruiting neutrophils?
IL8
What do you suspect if there are tons of neutrolphils?
IL8
What do you suspect if there are tons of neutrolphils?
IL8
What do activated macrophages do?
Activated macrophage will release tons of IL 1, 6, 8 and TNF alpha activating all the macrophages around it to kill the organism
What is LCI?
Lymphocyte cytotoxic immunity
What mediates LCI?
NK
What is on the surface of NK?
No CD3 of alpha beta or gamma delta chains, no antigen receptors
Why does NK not kill RBC?
RBCs are not killed as they have neither inhibitory or activating ligand so NK cell does not know they exist
How does NK cell activation work?
- MHCI cellshave both inhibitory/activating ligand for NK
- When NK cell binds both, it leaves cell alone
- Altered, or absent MHC I cannot stimulated negative signal telling NK cell to not kill things
- In such cases NK cell releases granules killing target cell
Two manners of LCI?
Non specific - NK
Specific - CD8
What leads to optimal CD8 activation?
Parallel activation of NK cells, Heler T , and presence of memory cells
What activates Th1
IL 12/18
What activates Th1
IL 12/18
Signals needed for CD8 activation?
Antigen specific is first and INF is second signal
What is CD8 powerless without?
CD4
What promotes TH2?
Soluble antigens and extracellular pathogens promote TH2
Major source of IL4?
Major source of IL4 is the TH2 cell itself
What can suppress TH1 in TH2 reaction?
IL4, IL10, IL13
How do B cells present antigen?
B cells present in MHCII, not in antibodies on surface
What is IGG?
Bind viral antigen in serum marking it for destruction by macs and neutrophils who will phagocytose IGG/antigen complex for destruction
What releases IGG?
Plasma cells
Trio of cytokines in Th17 response?
IL6, IL23, TGFbeta
Trio of cytokines in Th17 response?
IL6, IL23, TGFbeta
What is unique to Treg?
CD25