T Cells

Lymphocytes

The cellular portion of the adaptive immune system is?

CD4 and CD8 T cells

What are the main types of T cells?

CD8 T cells

Which class of T cells is also known as cytotoxic T cells?

Helper T cells

CD4 T cells are also known by what name?

B cells, T cells, and natural killer cells

The class of lymphocytes includes which cell types?

Small, mononuclear with basophilic cytoplasm

In general, how do lymphocytes appear under the microscope?

Plasma cell

A fully differentiated form of a B cell is a?

With a swollen cytoplasm with a per-nuclear halo due to up regulation of Golgi apparatus

How do plasma cells appear?

CD8 T cells

Which lymphocytes do natural killer cells appear similar to under the microscope?

False (CD4 cells are helper T cells)

True or False: Both CD4 T cells and NK cells have cytotoxic functions

Alpha beta chain or gamma delta chain

What are the different chains of the T cell receptor?

Alpha beta T cells

Which T cell types are seen more commonly in humans and rodents?

Ruminants

Gamma delta T cells are seen in which species?

Three; to act as a fail-safe

How many signals are required for naive T cell activation? Why is this?

The T cell receptor (TCR) binds to a molecule of MHC which is bound to an antigen

The first signal required in the activation of T cells is?

Co-stimulatory receptors on T cells bind to the antigen

After the T cell receptor has bound to a presenting MHC...

Co-stimulatory cytokines

The third signal of T cell activation includes which types of cells?

The third signal; co-stimulatory cytokines

Which step of the activation process is critical for proper differentiation of T cells?

TCR, CD3, and CD4/CD8

The three components of the T cell receptor complex are...

TCR

Which portion of the T cell receptor complex recognizes antigen?

CD3

Which portion of the T cell receptor complex is responsible for a stronger signal when an antigen is recognized?

Stabilization

What function of CD4/CD8 have in the T cell receptor complex?

MHC class II

T cells binding to which class of MHC is more stable?

True

True or False: All T cells have CD3

Mediates signaling and cell activation

What is the major function of CD3?

Intracellular; MHC I

CD8 is found from (extracellular/intracellular) sources and on cells which recognize antigens on MHC ___

A variable end and a constant end

The basic structure of a T cell receptor includes which parts?

Variable end

On which portion of the T cell receptor does the antigen bind?

Extracellular

MHC class II molecules present what kind of antigen?

False

True or False: Intracellular pathogens can only be presented on MHC I

An extracellular pathogen is phagocytized and presented by APCs through MHC I

What is the process of cross-presentation?

Broken down into linear peptides

T cells only recognize antigens when they are...

Peptides that are presented by MHC

How are antigens defined?

Must fit into the specific antigen, and must fit the part of the MHC holding the antigen

In order to be activated, the T cell receptor must have which two things happen?

Co-receptor type

The MHC type must match with what other property of the T cell?

A protein made by the pathogen locks TCR:MHC specificity and cytokines are released non-specifically

Pathogens such as staphylococcal enterotoxin can activate a large amount of T cells at once. How does this occur?

CD28, CD80 and CD86

Which specific ligands are associated with the second step of T cell activation?

CTLA-4

When T cells begin to produce less CD28, they begin producing what other substance?

True

True or False: CTLA-4 and CD28 bind to the same ligands

Inhibitory; prevents autoimmune or hyper immunity responses

CTLA-4 has what effect on T cells? Why is this important?

Stimulatory

CD-28 is a co-(stimulatory/inhibitory) molecule

Th1

IL-12 and IL-gamma produce what type of T cells?

IL-2 and TGF-beta

Which cytokines lead to the differentiation of T regulatory cells?

Th17

IL-6 and TGF-beta cause the differentiation of which T cells?

It becomes tolerant or anergic

If all three signals in the T cell activation process are not present, what is the fate of the T cell?

Telling other cells what to do

What is the general function of CD4 T cells?

Secrete transcription factors which regulate different functions later in maturation

How do cytokines determine the differentiation of T cells?

Th1, Th2, Th17, and Treg

The major subpopulations of T helper cells are?

Th1

Which subset of T cell can cause issues such as granulomas and autoimmunity when overactive?

Asthma, allergy, dermatitis

Th2 cells can cause which issues if overactive?

Th17

Rheumatoid arthritis or IBD is a complication of which overactive cells?

Viruses and bacteria

Th1 cells defend the body against which pathogen types?

Th2

Which T cells defend against parasites?

Bacteria and fungi

Th17 cells protect against which pathogens?

Tregs

Which subset of T cells is strongly associated with autoimmune and immune suppression issues?

Co-stimulation is not required

On a second exposure of an antigen, what is different about the T cell activation process?

Linear peptides presented by MHC

TCR recognizes ______

TCR:MHC, co-stimulatory signal, and co-stimulatory cytokines

Naïve T cell full activation requires ______

Macrophages, dendritic cells, and B cells; present antigen on MHCII

Professional APCs include ___, because they ____

Many; predominant

We expect to see ___ cytokines at once in vivo, but the ___

cytokine defines the disease type