Term
| What composes the T-cell receptor, and what are it's characteristics? |
|
Definition
αβ chains- it resembles the Fab portion of an antibody, but is univalent
-the TCR is never secreted
-MUST RECOGNIZE ANTIGEN IN CONJUNCTION WITH MHC
-has a V and a C region
-there is another gamma-delta chain styling, but the majority of TCR use the αβ style |
|
|
Term
| What function does CD3 have on T-cells? |
|
Definition
CD3 is analogous to Igα and Igβ on B-cells
-the transmembrane part is responsible for bioactivity
-CD3 is responsible for T-cell activation and differentiation |
|
|
Term
| How is the signal cascade initiated on CD3? |
|
Definition
| ITAM is phosphorylated on CD3- this makes CD3 capable of binding to ZAP70- this initiates the signal cascade |
|
|
Term
| Where and how does T-cell development occur? |
|
Definition
Progenitor T-cells are released from the BM and migrate to the thymus for education
-T CELLS MUST BE SELECTED FOR PRECISELY via positive and negative selection |
|
|
Term
| Where in the thymus are T-cells selected? |
|
Definition
| In the cortex- immature lymphocytes |
|
|
Term
| Where in the thymus are T-cells matured? |
|
Definition
| In the medulla- cells that survive selection become mature thymocytes |
|
|
Term
| What surface markings do progenitor T-cells have? |
|
Definition
|
|
Term
| What surface markings do pre T-cells have? |
|
Definition
| EVERYTHING- CD3,4,8 (+) also TCR(+) |
|
|
Term
| When does expression of TdT occur for recombination of the variable region of the TCR? |
|
Definition
| Through the time in the Thymic Cortex |
|
|
Term
| What shows up on the T-cells in the Thymic Cortex? |
|
Definition
|
|
Term
| Where does CD4 vs CD8 differentiation occur? |
|
Definition
|
|
Term
| What does positive selection ensure? |
|
Definition
That αβ TCR's will bind to self MHC
-that they can recognize MHC |
|
|
Term
| What does negative selection ensure? |
|
Definition
-That there isn't TOO much affinity for MHC, otherwise they might kill normal self cells
-High-affinity cells are removed at this point |
|
|
Term
| Where does initial antigen contact happen? |
|
Definition
| Secondary Lymphoid Tissue (Spleen, LN, etc) |
|
|
Term
| What happens if a patient cannot make β-2 Microglobulin? |
|
Definition
Remember, β-2 microglobulin is a component of the Class I MHC
- if it is absent, there can be no selection for CD8 cells so there are no cytotoxic T-cells |
|
|
Term
| What is the consequence of overactive T-cells? |
|
Definition
|
|
Term
| What protein interaction is the second step after T-cell binds with antigen+MHC? |
|
Definition
| B7 on the APC interacts with CD28 on the T-cell |
|
|
Term
| What protein is constitutively expressed on dendritic cells? |
|
Definition
B7- to interact with CD28
DENDRITIC CELLS ARE THE ONLY CELLS THAT CAN ACTIVATE NAIVE T-CELLS |
|
|
Term
| What do macrophages require to be able to activate naive T-cells? |
|
Definition
| IFN-γ and they can only do so after contact with antigen |
|
|
Term
| Name 3 Antigen Presenting Cells |
|
Definition
| Dendritic Cells (best), B-cells, Macrophages |
|
|
Term
| What is the major cytokine to activate macrophages? |
|
Definition
|
|
Term
| What must T-cells find on macrophages for adhesion to occur? |
|
Definition
| CD28 on T-cells must find B7 on macrophages |
|
|
Term
| What 3 proinflammatory cytokines do macrophages release? |
|
Definition
|
|
Term
| What other signal does the T-cell need for activation once binding with the macrophage occurs? |
|
Definition
|
|
Term
When activated, what receptor do Helper T-cells express?
What does it's binding cytokine cause? |
|
Definition
| IL-2 receptor; IL-2 causes T-cell proliferation |
|
|
Term
| What does ZAP70 become after it is recruited by the TCR? |
|
Definition
|
|
Term
| What happens if ZAP70 is constitutively turned on? |
|
Definition
| Acute Lymphocytic Leukemia |
|
|
Term
| What intracellular ion concentration increases when T-cell signalling occurs, and what does T-cell signalling lead to? |
|
Definition
| Intracellular calcium increases; activation of T-cells leads to cell division and cytokine production |
|
|
Term
| How do superantigens bind to the TCR? |
|
Definition
| Outside of the cleft, leading to a reduction in specificity- NUMEROUS T-cell clones are activated |
|
|
Term
| What is the superantigen made by Staph Aureas? |
|
Definition
| Toxic Shock Syndrome Toxin |
|
|
Term
| What type of reaction do intracellular parasites, bacteria, and fungi induce? |
|
Definition
| Delayed-type with TH1 and macrophage activation |
|
|
Term
|
Definition
Precursors to differentiated helper T-cells
-can make any and all cytokines
-can differentiate into TH1 or TH2 |
|
|
Term
What are TH1 cells?
In what type of immunity are they found? |
|
Definition
TH1 cells are associated with CELL MEDIATED IMMUNITY
-delayed hypersensitivity helps development of CD8 cytotoxic T-cells
-TH1 cells produce- IFN-γ, IL-2, TNF-Beta, IL-3, and GM-CSF
-TH1 cells use IFN-γ to downregulate TH2 cells |
|
|
Term
What are TH2 cells?
In what type of immunity are they found? |
|
Definition
TH2 cells are HUMORAL IMMUNITY-
-they work on EXTRAcellular pathogens
-help B-cells produce antibody
-induce CLASS SWITCHING
-proliferate eosinophils and mast cells
-produce: IL-4, IL-5 and IL-10
-down regulate TH1 by secreting IL-10 |
|
|
Term
| What downregulates TH2 response? |
|
Definition
|
|
Term
| What downregulates TH1 response? |
|
Definition
|
|
Term
What is required for clonal expansion of Cytotoxic T-cells, and their effector function?
Where does it come from? |
|
Definition
|
|
Term
|
Definition
| Punches holes in membranes by forming pores |
|
|
Term
|
Definition
| Enzymes that damage the target cell |
|
|
Term
| What cytokines are secreted by cytotoxic T-cells to induce apoptosis? |
|
Definition
|
|
Term
| What is the significance of Fas? |
|
Definition
| When FasL on cytotoxic T-cells binds with Fas on the target cell, apoptosis is induced |
|
|
Term
| What markers are found on Cytotoxic T-cells and what do these cells do? |
|
Definition
TCR, CD3, CD8, CD2- they have specific antigen recognition at the TCR, requiring Class I MHC-
-use perforing and granzymes, when triggered by IFN-γ and TNF Beta, to kill the target cell |
|
|
Term
| What markers do NK cells have and what do these cells do? |
|
Definition
CD16, CD56, CD2- cause ADCC by IgG- DOES NOT REQUIRE MHC
***IF MHC IS RECOGNIZED BY NK CELLS, APOPTOSIS IS INHIBITED*** |
|
|
Term
| What markers are found on Macrophages and how do these cells act? |
|
Definition
CD-14
-when prompted by TNF alpha, they secrete Nitric Oxide, enzymes, and oxygen radicals to destroy the pathogen |
|
|
Term
| What are Interdigitating Dendritic Cells? |
|
Definition
| the only cells capable of activating naive T-cells |
|
|
Term
| What are Follicular Dendritic Cells? |
|
Definition
Helpers to forming memory and plasma cells
-DO NOT EXPRESS CLASS II MHC
-have long dendrites with C and Ab receptors |
|
|
Term
How is antigen cleared from:
-tissues?
-blood?
-mucosa? |
|
Definition
tissues- draining lymph nodes
blood- sent to spleen
mucosa- MALT |
|
|
Term
| What are the components/regions of a lymph node? |
|
Definition
Remember, they have B-cell and T-cell areas
-afferent lymphatics (in)
-efferent lymphatics (out)
-post-capillary venules
Cortex, paracortex, medulla, germinal center |
|
|
Term
| Where in the lymph nodes do we find B-cells? |
|
Definition
|
|
Term
| Where in the lymph nodes do we find T-cells? |
|
Definition
|
|
Term
| What happens in the LN germinal center? |
|
Definition
| Most proliferation, class-switching, and affinity maturation |
|
|
Term
| What can be found in the LN medulla? |
|
Definition
| Plasma cells secreting antibody |
|
|
Term
| What are antigens carried in to get to the spleen? |
|
Definition
|
|
Term
| Where in the spleen are B-cells found? |
|
Definition
| Marginal zone, arranged in follicles- when they meet antigen they form secondary follicles |
|
|
Term
| Where in the spleen can T-cells be found? |
|
Definition
| Around the artery in the Periarteriolar Lymphoid Sheath (PALS) |
|
|
Term
| What does the quantity of antigen-specific lymphocytes look like withing 24 hours of infection? |
|
Definition
| There are very few, because they have all rushed ot the LN or spleen to activate |
|
|
Term
| What directs the flow of B and T cells through secondary lymphoid tissue? |
|
Definition
| CAMs- Cell Adhesion Molecules- |
|
|
Term
| What specialized cells function as a secret door to the lymphatics for naive cells? |
|
Definition
| High Endothelial Venules (HEV's) |
|
|
Term
|
Definition
| The movement of naive cells from blood to lymph |
|
|
Term
| What happens in rolling adhesion? |
|
Definition
| Selectins on the lymphocytes bind CD34 on vascular endothelium |
|
|
Term
|
Definition
Leukocyte Adhesion Deficiency- CAM (integrin) is missing
-CAM mediates tight binding, which is needed to get lymphocytes from blood to infected area
-super high WBC in blood, but NO PUS because they can't get to tissues
-recurrent bacterial infections and impaired wound healing
-first shows up in the umbilical stub |
|
|
Term
| What forms a separate secretory system in which plasma cells can secrete tons of IgA? |
|
Definition
|
|
Term
| What are the special cells through which antigen enters Peyers patches? |
|
Definition
|
|
Term
| What type of epithelium contains M-cells? |
|
Definition
| Follicle-associated Epithelium (FAE) |
|
|
Term
| What happens in the mucosa after lymphocyte activation? |
|
Definition
Lymphocytes enter lymph, go through mucosal nodes and the thoracic duct, and pass from the blood back to the lamina propria
-they become IgA secreting plasma cells |
|
|
Term
| What can be found in the lamina propria? |
|
Definition
| Large concentrations of activated T-cells, B-cells, and IgA plasma cells |
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