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17 Cards in this Set
- Front
- Back
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Whats naive T cell marker? Why is it important?
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Naive T cells express CCr7. It's a receptor for CCL19 and CCL21 which is expressed by a lymph node to attract naive T cells.
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What kind of cells are usually responsible for antigen presentation in the lymph nodes and why?
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Dendritic cells, because they are migratory and do not degrade the antigen. Their main purpose is antigen presentation, unlike macrophages.
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How are peptides processed for presentation?
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Through the endogenous or exogenous pathway.
endogenous = MHC I exogenous = MHC II |
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What's t cell anergy and how does it happen?
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If a t-cell binds a MHC/peptide complex and there's no costimulatory signal.
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What's Signal 1?
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When the TCR binds a peptide/MHC complex.
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What's Signal 2?
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When CD28 on T cell binds B7 on the APC. Needed to activate the T cell. B7 isn't expressed unless there's an infection.
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What is associated with the TCR to induce a signal?
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In immunology, the CD3 T-Cell Co-Receptor (CD stands for cluster of differentiation) is a protein complex and is composed of four distinct chains. In mammals, the complex contains a CD3γ chain, a CD3δ chain, and two CD3ε chains. These chains associate with a molecule known as the T cell receptor (TCR) and the ζ-chain to generate an activation signal in T lymphocytes
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What's an ITAM?
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The intracellular tails of the CD3 molecules contain a single conserved motif known as an immunoreceptor tyrosine-based activation motif or ITAM for short, which is essential for the signaling capacity of the TCR.
Phosphorylation of the ITAM on CD3 renders the CD3 chain capable of binding an enzyme called ZAP70 (zeta associated protein), a kinase that is important in the signaling cascade of the T cell. |
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What's TAP?
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Transporter associated with Antigen Processing. It's used in the Endogenous (MHC I) pathway.
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Where are peptides loaded in the Exogenous pathway?
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Peptides are loaded onto MHC II molecules that are present in the late endosomes.
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How do T cells enter and exit lymph nodes?
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Naive T cells enter through the HEV and when they're retained and activated; they differentate and proliferate into a clone of effector T cells.
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How do naive t cells bind to dendritic cells in the lymph node?
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The t cells express LFA-1. This binds to ICAM being expressed by the dendritic cells, subsequent binding of the TCR causes a conformational change in LFA-1 resuglint in a higer affinity for ICAMs expressed by dendritic cells.
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What's the immunological synapse?
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It's the region of contact and communication between the T cell and the APC.
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What's IL-2? low- vs. high affinity receptors?
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Naive T cells express the low affinity receptor for IL-2. Activated T cells express the HIGH affinity receptor, and secrete IL-2. IL-2 is critical for proliferation and clonal expansion.
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In general, what do TH1 cells do?
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They secret IL-2 and IFNγ which stimulate Mϕ response. IFNγ inhibits supresses diff of TH2 cells.
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In general, what do TH2 cells do?
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Secrete IL-4 and IL-5 Activation of B cells to make antibodies/class switching. IL4 suppresses diff of TH1 cells.
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How are B cells activated by T cells?
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When T cells bind the MHC/peptide complex presented by B cells, CD40L on the Tcell interacts(signal 2) with CD40 on the B cell. This activates NFkB and results in the T cell producing IL4. IL4 results in B cell proliferation and differentiation.
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