Primer 30 - T Cells Flashcards Preview

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Flashcards in Primer 30 - T Cells Deck (36):

What does Interferon gamma (IFN-gamma) do?

Stimulates macrophages.


What does IL-10 do?

Inhibits T cells and macrophages.


What do IL-4 and IL-5 do?

They stimulate B cells.


Where are T cells made and where do they differentiate?

They are manufactured in the bone marrow and they migrate to the thymus to differentiate.


Describe the maturation process of the T cells.

When they arrive in the Cortex of the thymus, they are immature (they are both CD4+ and CD8+). As they mature, they lose the one positivity to become CD8 cytotoxic T cells or CD4 helper T cells.


Where does Positive selection of T cells takes place?

Thymic cortex.


Where does Negative selection of T cells takes place?

Thymic corticomedullary junction.


What happens to the T cells that are selected in the negative selection?

They are removed by apoptosis.


What are the two kinds of T helper cells?

Th1 and Th2 cells.


What cytokine makes the T helper cell differentiate to Th1 cell and what factor for Th2?

Th1: IL-12.
Th2: IL-4.


How do we stimulate the production of IL-12 cells and what does it do?

Viral infections stimulate the production of IL-12 that stimulates the production of Th1, which in turn stimulates the production of IL-2 and INF-gamma.


What inhibits the production of Th1 and who is responsible for it?

Th1 is inhibited by IL-10, which is released by Th2 cells.


What does Th1 stimulate?

The production of IL-2(which stimulates the production of T cells and cytotoxic T cells.) and INF-gamma (Which stimulates macrophages).


What does Th2 stimulate?

Production of IL-10 which inhibits the development of Th1 cells and IL-4 and IL-5 which stimulates the production of B cells.


What is MALT tissue?

The mucosa-associated lymphoid tissue (MALT) is a diffuse system of small concentrations of lymphoid tissue found in various mucosa sites of the body, such as the gastrointestinal tract, thyroid, breast, lung, salivary glands, eyes and skin.


In what sites of the bodies do we find more Th1 cells?

In the dendritic cells, skin and lymph node areas.


In what sites of the body do we find more Th2 cells?

Around the MALT (mucosa-associated lymphoid tissue) in order to stimulate IgA antibody production.


Where does the thymus come from?

From the epithelium of the third brachial pouch.


Where do mature T cells reside in the thymus?

In the medullar of thymus.


What are the two signals to activate T cells?

On the surface of the Th is the TCR + CD4 complex and CD28 receptor. Said receptors need to unite to a molecule presented by a MHCII and B7 (AKA CD 80 or CD86), respectively on the cell that is presenting the molecule. This is called co-stimulation, stimulating the Th cell to produce cytokines.


What do cytotoxic T cells do?

They look for virally infected cells to kill, neoplastic cells and non-self selfs (like donor grafts).


What relevant receptors are on the surface of cytotoxic T cells in order to activate them?

Cytotoxic T cells have TCR+CD8 complex that recognizes an antigen presented in MHC I and CD28 that combines with B7 molecule on the cell that is presenting the antigen.


How do we activate B cells to make immunoglobulins?

There are 4 main steps; 1.Endocytosis of antigen by B cells 2.Antigen is presented to a Th cell by using the MHC II found on APCs. 3. Use of costimulatory signal of CD40 receptor on B cells and CD40 ligand on Th cells. 4. The first 3 steps have induced the Th2 cells to generate IL-4,5,and 6 cells (These IL now promote activation and immunoglobulin class switching of the B cells).


What does IL-2 do?

It is an important cytokine that is a T cell stimulator.


Where do CD8 cells go after maturing in the thymus?

In the lymph nodes where they spend most of their time.


How do cytotoxic T cells attack their targets and how?

By inducing apoptosis by the release cytotoxic granules that have preformed proteins like perforin and granzyme by the CD8 cells. They also express a molecule called FAS ligand, interacting with the fas receptor in the host cell, resulting in apoptosis.


What are the two types of Regulatory T cells?

T regulatory CD4 cells and T suppressor CD8 cells.


What does T regulatory CD4 cells do?

They express CD4 and CD25. They inhibit B cell antibody production and inhibit the generation of autoimmune disease.


What do T suppressor CD8 cells do?

Suppress graft rejection and inhibit some autoimmune diseases.


What do NK cells do?

They can kill other cells by using perforin and granzyme to induce apoptosis. They secrete IFN-gamma (which stimulates macrophages).


How are NK cells induced to kill?

When appropriate ratio of activation signals are present on the target cell and the absence of specific inhibitory signals on the target cell (MHC I). Because NK cells do not need require helper T signals (like cytotoxic T cells) to attack, they are part of the early innate immune response to kill tumor and virally infected cells.


What enhances the activity of NK cells?

Their activity is enhanced by IL-2, IL-12, interferon beta and interferon alpha.


Which surface markers are on the surface of NK cells?

CD 16 and CD 56.


What does CD16 do and where is it found?

It binds to the constant region of antibodies. Those with this CD can recognize and kill immunoglobulins coated cells by ADCC. They are found on NK cells, macrophages, monocytes, and neutrophils.


Which cytokines are produced by Th1 cells? Which cytokines are produced by Th2 cells?

Th1: IL-2 and IFN-gamma which leads activation of CD8 cells and macrophages.
Th2: IL-4, IL-5, IL-10, which lead to activation of B cells and Ab production.


Which cytokines inhibit Th1 cells? Which cytokines inhibit Th2 cells?

Th1 is inhibited by IL-10 while Th2 is inhibited by Th2.