Term
| Give an example of molecular antigens that would be fought by antibody-mediated immunity |
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Definition
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Term
| Give an example of extracellular infections that would be fought by antibody-mediated immunity |
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Definition
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Term
| Give an example of an extracellular phase of intracellular infection that would be fought by antibody-mediated immunity |
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Definition
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Term
| Give an example of a cellular antigen that would be fought by antibody-mediated immunity |
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Definition
Transfusion reaction
(cellular antigens are rare for antibody-mediated immunity) |
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Term
| Which type of immunity (antibody or cell mediated) would affect toxins, antigens, or extracellular infections? |
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Definition
| Antibody-mediated immunity |
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Term
| Which type of immunity (antibody or cell mediated) would affect intracellular or cellular infections? |
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Definition
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Term
| Give an example of a molecular antigen that would be fought by cell-mediated immunity |
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Definition
Contact dermatitis
(Cell-mediated immunity rarely fights molecular antigens) |
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Term
| Give an example of a faculative intraceullar infection that would be fought by cell-mediated immunity |
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Definition
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Term
| Give an example of a obligate intracellular that would be fought by cell-mediated immunity |
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Definition
| Rickettsia, chlamydia, viruses |
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Term
| Give an example of a cellular antigen that would be fought by cell-mediated immunity |
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Definition
| Transplants, tumors, virus-infected cells |
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Term
| Which immune defense specifically is an issue for organ transplants? |
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Definition
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Term
| What is the difference between the immunogens B-cells recognize and the immunogens T-cells recognize? |
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Definition
B cells bind complete immunogen molecules
T cells bind metabolized immunogen fragments with MHC molecules |
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Term
| What five things do T-cell responses and B-cell responses have in common? |
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Definition
1.They are both specific yet heterogenous
2. They follow the same time course
3. Both require helper T cells
4. Both have primary and secondary responses
5. Both have memory |
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Term
| What does it mean when we say an immune response is heterogenous? |
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Definition
| Multiple antibodies attack an invader (polyclonal response) |
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Term
| Are T cell receptors considered immunoglobulins? |
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Definition
No, because they are an effector anchored to the T-cell membrane.
However, they are analogous in structure and genetics to B-cell receptors |
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Term
| Immunoglobulins are the major products of B cells. What are the major products of T cells? |
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Definition
| Cytokines (aka lymphokines) |
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Term
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Definition
Effector proteins that T-cell produces in response to an infection.
Cytokines are not specific for an antigen, but the T-cell itself is specific. |
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Term
| What do CD4+ T-cells recognize? |
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Definition
| Processed immunogens complexed with Class II MHC |
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Term
| What do CD8+ T-cells recognize? |
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Definition
| Processed immunogens complexed with Class I MHC |
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Term
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Definition
A 6 molecule complex closely associated with the TCR
Involved in signal transduction |
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Term
| What do all T cells have on their surface? |
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Definition
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Term
| What percentage of T cells express CD4? What percentage express CD8? |
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Definition
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Term
What does "CD" stand for?
(CD as in CD3, CD4, CD8) |
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Definition
Cluster of differentiation
Used to designate a variety of proteins on the surface of cells |
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Term
| Is MUROMONAM-CD3, the monoclonal antibody specific for CD3, a specific immunosupressive antibody? |
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Definition
No. Monoclonal antibodies are very specific, but CD3 is present on all T cells.
Therefore, it makes sense that MUROMONAM-CD3 would be used to manage acute renal allograft rejection. |
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Term
| List the cells in the order that they evolve in T-cell development |
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Definition
1. Stem cell
2. Double negative thymocyte
3. Double positive thymocyte
4. Mature (single positive) CD4 or CD8 T cell |
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Term
Define double negative thymocyte.
Where in the body would you see one? |
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Definition
A developing T-cell that has only TCR or CD3 (and lacks both CD4 and CD8)
Only present in the thymus |
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Term
Define double positive thymocyte.
Where in the body would you see one? |
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Definition
A developing T cell that has both CD4 and CD8
Should be only present in the thymus. Presence outside of thymus indicates pathology. |
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Term
| Describe the two processes a double positive thymocyte undergoes to become a mature T cell |
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Definition
1. Positive selection- promotes thymocytes whose TCRs recognize self-MHC
2. Negative selection- deletes the thymocytes whose TCRs recognize self-proteins |
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Term
| Can non-immune cells be antigen presenting cells? |
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Definition
| Yes, they can be. All nucleated cells express MHC Class I. So, strictly speaking any nucleated cell can be an Antigen Presenting Cell. |
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Term
| Describe the structure of a TCR |
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Definition
Disulfide-linked heterodimer anchored by transmembrane segments:
α-Chain — MW ~ 45,000 + β — MW~ 55,000
[Analogous to Ig Fab] |
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Term
| Do TCRs undergo somatic hypermutation? |
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Definition
| No. The diversity of TCR is the same for Ig up until Ag is encountered, it doesn't diversify afterward. |
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Term
| How many V/D/J/C regions are there in a TCR α-chain? |
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Definition
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Term
| How many V/D/J/C regions are there in a TCR β-chain? |
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Definition
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Term
| Do TCRs have effector functions like Igs? |
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Definition
No.
TCRs activate the T cell to release cytokines. |
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Term
| Define γδ T cell receptors |
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Definition
The "other" T cell receptor that doesn't need MHC to produce cytokines (especially for tumor cells)
May be a relative of NK cells
May play a role in food tolerance |
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Term
| Where are γδ T cell receptors found? |
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Definition
| Mostly in intraepithelial spaces, not really in peripheral blood |
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Term
| What sort of ligands do γδ T cell receptors recognize? |
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Definition
Not short peptides like regular TCRs
They recognize small bacterial phosphoantigens |
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Term
| What is the true purpose of a CD4/CD8 protein? |
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Definition
| To stabilize the reaction of a TCR and an MHC |
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Term
| What 2 proteins act as a co-stimulating fail-safe mechanism for a T cell? |
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Definition
CD28 on naïve T cell
and
B7 on dendritic cell |
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Term
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Definition
| Rendering a T-cell inactive |
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Term
| What happens if CD4 and MHCII bind but B7+CD8 do not? |
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Definition
| The T-cell is rendered anergic to prevent autoimmunity |
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Term
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Definition
| Certain bacterial toxins and retroviral proteins that can bind to both MHC class II molecules and TCR β-Chains without antigen processing |
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Term
| Where do superantigens bind? |
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Definition
| Outside the peptide-binding groove of the MHC and outside of the TCR binding site to the Vβ segment |
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Term
| How many T-cells can superantigens active? |
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Definition
Since superantigens recognize only Vβ segments (20-30 known), they may activate 1-10% of the T Cells compared to perhaps 1:10,000-100,000 that are activated by an antigen.
This is still quite a lot of T cells, enough to cause shock |
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Term
| What pathology can superantigens cause? |
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Definition
First profound immunostimulation, then profound immunosuppresion
Massive T Cell activation and the resulting cytokine release contributes to the pathology of several conditions such as the toxic shock syndrome induced by some strains of Staph. aureus.
Sometimes they can induce apoptosis |
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