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74 terms

Cellular Immunity III

STUDY
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What are the three types of professional antigen presenting cells
Dendritic cells, macrophages, B cells
How do dendritic cells take up antigens
pinocytosis and phagocytosis
What kind of antigens do dendritic cells present
Peptides, viral antigens, allergens
How do macrophages take up antigens
Phagocytosis
What kind of antigens do macrophages present
Particulate antigens, intracellular and extracellular pathogens
How do B cells take up antigens
Through antigens specific receptors Ig
What kind of antigens do B cells present
Soluble antigens, toxins, viruses
Where most dendritic cells found
In the skin or mucosal tissues as Langerhans cells
What is the best APC
Dendritic cells
Once a dendritic cell or macrophage presents a specific antigen a T cell recognizes what happens to the T cell
It begins to proliferate and differentiate to effector cells
How do T cells enter lymph nodes or regular tissues
The of the same mechanism of neutrophils that is rolling tight adhesion diapedesis and tissue migration
What do selectins do
They allow lymphocytes to home to lymph nodes or to sites of infection
What do ICAMS do
They allow T cells to talk to APC's
Where can Naïve T cells enter lymph nodes
afferent lymphatics or the blood
What happens to the the adhesion molecules of T cells once they become activated
They change
Describe the intracellular signaling pathway that turns on inside an activated T cell
Tyrosine kinases activate Phospholipase Cg. This cleaves PIP2 to DAG and IP3. Dag and calcium activate Protein Kinase C (PKC). IP3 causes the release of calcium. The release of calcium activates the phosphatase calcineurin. PKC and calcineurin activate transcription factors NFkB and NFAT which induce the cell to divide.
What does receptor associated tyrosine kinase activate
PLCg
What does PLCg do
cleaves PIP2 to DAG and IP3
What does DAG and calcium activate
PKC or protein kinase C
What does IP3 do
causes the release of calcium from the ER
What does the release of calcium do
activates calcineurin
What do PKC and calcineurin do
activates transcription factors NFkB and NFAT
What do the transcription factors NFkB and NFAT do
induce the T cell to divide
What transcription factors induce the t cell to divide
NFkB and NFAT
Is engagement of the T cell via the TcR enough to turn on the T cell
No, it requires co stimulation
What is co stimulation mediated by
CD80 and CD86 on the APC which binds to CD28 on naïve T cells to deliver the costimulation
What co stimulatory molecules are on the T cell
CD28
What costimulatory molecues are on the APC
CD80 and CD86
What happes to the T cell once the response to the non self antigen is complete
The T cell upregulates expression of CTLA4
What does CTLA4 do
It binds to CD80 and CD86 better and shuts down the T cell response
What happens to the T cell in the absence of costimulation
It becomes anergic or permanently inactive
What is the source and effects of IL1
APCs and Inflammation
What is the source and effects of IL2 and IL12
Th1 and T cell growth
What is the source and effects of IL4 and IL5
TH2 and humoral immune response such as IgA, IgG1, IgE antibody production and class switching
What is the source and effects of IL 10
Th2 (Treg) inhibits Th1 and upregulates MHC class II
What is the source and effects of IFN gamma
Th1 and inhibits Th2, upregulates MHC class I and II
What is the source and effects of TNF
Th1 and inflammation
What is the IL2 receptor
CD25
What happens to activated T cells with regards to IL2
they begin to make their own IL2 and change receptors from a low affinty dimer to a high affinty trimer
What pathway is the signaling for IL2 mediated by
PI3
What is a crucial signaling molecule in the PI3 pathway
mTOR
What are the two subsets of effector T cells
CD8 and CD4
What do CD8 t cells make
perforin and granzymes and Fas
What is the function of CD8 t cells
cytotoxic
What is the function of perforin
it perforates cells
What is the funciton of Granzymes
it is injected into a cell and begins the cell death pathway
What is the funciton of Fas
interacts with the Fas ligand and also begins the cell death pathway
What are the three subsets of CD4 cells
Tregs, Th1 and Th2
What do Treg T cells do
down regulates th1 via IL10
What do TH1 cells do
inflammatory and cellular immune response by making TNF and IL12 and INF gamma secretion. Host defense against intracellular microbes
What do th2 cells do
humoral antibody immune response IL4 il5 il13 secretion, host defense against helminths and allergic reactions
What drives naïve cd4 tcells down the th1 pathway
IL12, IFN gamma
what driives naïve cd4 tcells down the th2 pathway
il4
What happens do down or upregulate the th1 or th2 responses
th2 secretes TGF beta and IL10 which inhibit activation and growth of TH1, th1 secretes IFN gamma which inhibits proliferation of th2 cells
Why do cd8 cells not require further costimulation after being stimulates
the IL2 they produce is an autocrine growth factor
how do ctl's kill their targets
inducing apoptosis via perforins and granzymes
How else can apoptosis be triggered via CTl's
interaction of CTL FASL with the Fas in the target cell
what is the function of Th1 cells
cellular immunity
what is the funciton of the th2 cells
humoral imminity
what do th1 cells talk to
cd8 cells and macrophages
what do th2 cells talk to
b cells
What do th1 cd4 cells activate
they activate macrophages to become highly microbiocidal
how do th1 cd4 cells accomphlish this microbiocidality
the interaction between cd40 on the macrophage and cd40L on the t cell and via th1 cytokines
what happens when intracellular pathogens cannot be totally eliminated
th1 cells induce granuloma formation
where are granulomas commonly seen and why
tuberculosis, parasitic infections and granulomatous disease. The pathogens have evolved mechanisms to resists macrophage mediated killing
How do th2 cells talk to b cells
through the CD40L and CD40 interaction along with IL4 and IL5
what interaction is required for class switching
CD40-CD40L
What happens when th2 cells talk to B cells
B cell proliferation and differention into antibody secreting plasma cells
Where does the B cell proliferation occur
germinal center
what antibodies are produced when IL4 is released from th2 cells to the b cells
IgG4 and IgE
What does IgE cause
mast cell degranulation
what does IL5 do
recruits eosinophils to activate to kill helminths
what is the difference between protective immunity and immunological memory
protective immunity is due to recent infections that have induced antibodies, immunological memory is due to a memory response from a previous infection from a while ago
Which is better the primary or secondary immune response
the secondary due to the affinty of the antibodies and and the freguency of the antigen specific b cells