Term
| Effective CD4+ T cells that survive the screening process in the thymus are termed |
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Definition
naive (Thp)
Need to further differentiate to perform their biological function |
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Term
| Primary immune responses occur in |
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Definition
| Secondary lymphoid tissues |
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Term
| Activation of T cells requires ? |
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Definition
| That antigen be displayed on surface of an APC in association with class 2 MHC / peptide |
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Term
| Why is dendritic cell most efficient APC ? |
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Definition
| Dendritic cell constitutively expresses both class 2 MHC and various costimulatory molecules whose counter-products are present on the T cell |
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Term
| When T cell interacts with peptide/MHC complex in absence of costimulatory interactions, the T cell becomes |
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Definition
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Term
| Naive CD4+ T cell activation is dependent on what signals ? |
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Definition
1) Peptide/class 2 MHC with TCR
2) Class 2 MHC with CD4
3) The B7 family of costimulatory molecules with their counter ligands, CD28/CTLA4
4)CD40 with its counter ligand CD40L/CD154
5)Various adhesion molecules on T cell interacting with counter molecules on APC |
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Term
| Class 2 MHC peptide on APC interactw with what on T cell ? |
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Definition
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Term
| Class 2 MHC on APC interacts with what on T-cell ? |
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Definition
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Term
| Why is interaction of CD28 with CD80/CD86 important ? |
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Definition
It is a critical signal in T cell activation leading to clonal expansion
This interaction triggers signal transduction events that lead to stabilization of mRNA for IL-2 |
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Term
| Antigen induced differentiation of a Thp proceeds how ? |
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Definition
| Thp to a ThO which becomes either Th1 or Th2 |
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Term
| THO cells secrete what cytokines ? |
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Definition
2, 4, I
IL-2, IL-4, IFNgamma |
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Term
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Definition
2, T, I
IL-2, TNF, IFNgamma |
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Term
| Th2 cells secrete what cytokines ? |
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Definition
IL-4
IL-5
IL-6
IL-10
IL-13
TGFbeta |
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Term
| In presence of IL-4, THO cells are driven to become |
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Definition
| TH2 cells and secret Type 2 cytokines |
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Term
| What is source of IL-4 before differentiation of Thp to TH2 phenotype? |
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Definition
Mast cells
Basophils
Non T cells |
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Term
| IFNgamma drives ThO cells to |
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Definition
| TH1 cells and secretion of Type 1 cytokines |
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Term
| How are Type 1 and Type 2 cytokines different ? |
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Definition
Type 1 cytokines support immune responses in which macrophages, NK cells, and CD8+ T-cells are effector cells.
Type 2 cytokines support B cell induced activation and support differentiation to plasma cells. Type 2 cytokines also support isotype switching to IgG1 and IgE |
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Term
| What is required for isotype switching to IgE? |
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Definition
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Term
| What cytokine down regulates Th1 cells/cytokines ? |
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Definition
| IL-4 and IL-10 , IL-10 does it via inhibition of IL-12 secretion by APCs |
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Term
| What cytokine inhibits TH1 cells ? |
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Definition
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Term
| CTLA-4/CD152 binds what ? |
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Definition
|
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Term
| Difference b/w CD28 and CTLA-4 ? |
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Definition
CTLA-4 is not expressed constitutively
and has a higher affinity for both B7-1 and B7-2 |
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Term
| CTLA-4 knockout mice show what ? |
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Definition
| An increase in the number of activated lymphocytes |
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Term
| Interaction of CD28 with B7 serves as a costimulatory molecule leading to enhanced expression of ? |
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Definition
| IL-2 and bcl-x (an anti-apoptotic factor) |
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Term
| CD28 and B7 engagement rescues T cells from apoptosis how ? |
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Definition
| By enhancing expression of bcl-x (which protects T cells from fas mediated apoptosis) |
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Term
| T cells stimulated only by peptide/MHC in absence of costimulation become |
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Definition
| anergic or undergo apoptosis |
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Term
| CD200 interaction with CD200R1 leads to ? |
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Definition
| Suppression of T-cell mediated immune responses |
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Term
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Definition
| T cells, B cells, and dendritic cells |
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Term
| Depletion of nTregs causes ? |
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Definition
| Enhances immune responses to pathogens |
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Term
| Genetic mutations of FOXP3 leads to ? |
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Definition
| Dysfunction of nTregs and IPEX syndrome |
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Term
| What 4 cytokines play a role in Thp differentiation to Th17 ? |
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Definition
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Term
| What cytokine helps to differentiate Thp to a/i Tregs ? |
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Definition
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Term
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Definition
| Adaptive-Induced T Regulatory Cells |
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Term
| a/i Tregs are charachterized phenotypically as ? |
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Definition
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Term
| Steps in the differentiation of TH17 cells includes what 3 stages ? |
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Definition
DAS
Differentiation
Amplification (mediated by IL-21)
Stabilization |
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Term
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Definition
Th17 cells play a role in immune response against extracellular pathogens that are not eliminated by CD4+ Th1 and CD4+ Th2 effector cells.
Effective against mostly fungal infections and also bacterial infections |
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Term
| CD4+ Th17 cells secrete what proinflammatory cytokines ? |
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Definition
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Term
| Role of Th17 cells in inflammation ? |
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Definition
| Th17 cells induce the secretion of inflammatory mediators (cytokines, chemokines, and matrix metalloproteinases) from macrophages |
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Term
| Autoreactive CD4+ Th17 cells do what ? |
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Definition
| Are highly pathogenic causing inflammation and severe autoimmunity |
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Term
| What two cytokines help induce differentiation of pCTL to CTL ? |
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Definition
|
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Term
| Conjugate formation b/w target cell and pCTL ? |
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Definition
Interaction of adhesion molecules CD2 and LFA-3, and LFA-1 and ICAM (1-3)
Also CD8 bind to class 1 MHC at a site distinct from which binds TCR |
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Term
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Definition
| Activation of CD8+ T-cells in response to an exogenous antigen |
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Term
| What is the "lethal hit" ? |
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Definition
| CTL-mediated lysis of the target cell |
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Term
| Destruction of target cells occurs via release of perforin by ? |
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Definition
| Both calcium dependent and calcium independent mechanisms |
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Term
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Definition
Group of antigens occurring in various bacteria and viruses that bind outside of the normal T-cell receptor site
They crosslink the CD4+ T-cell variable region.
Superantigens do not undergo processing and presentation by MHC molecules |
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Term
| Monoclonal activators of lymphocytes ? |
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Definition
T dependent antigens
T independent antigens
MHC-peptide |
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Term
| Polyclonal activators of lymphocytes ? |
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Definition
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Term
| What are first T cells to appear during embryonic development ? |
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Definition
| Thymus derived gamma/delta T-cells |
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Term
| The TCRs on gamma/delta and alpha/beta T-cells are expressed as a complex with ? |
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Definition
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Term
| One difference b/w alpha/beta T-cells and gamma/delta T-cells is ? |
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Definition
| Gamma/Delta T cell recognition of antigen is not uniform |
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Term
| Function of Gamma/Delta T-cells ? |
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Definition
Play a role in concert with alpha/beta T-cells in immunity to parasitic infection
Also clonal expansion of gamma/delta T cells recognizing heat shock protein related antigens are observed in malignancy, autoimmune disease, and transplantation |
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