T cells

Question 1

Which type of T cells kill virus infected cells?

Answer 1

CD8 Cytotoxic T cells

Question 2

Which type of T cells target microbes that persist in macrophage vesicles by activating the macrophages and help B cells produce antibodies?

Answer 2

CD4 Th1 cells

Question 3

Which type of T cells target helminths and provide help to B cells for antibody production, especially switching to IgE?

Answer 3

Cd4 Th2 cells

Question 4

Which Type of T cells targets klebsiella pneumonias and fungi by enhancing neutrophil response and promoting barrier integrity?

Answer 4

CD4 Th17 cells

Question 5

Which type of T cells targets all types of T cells by helping B cells isotype switch and product antibodies?

Answer 5

Tfh Cells

Question 6

Which type of T cells suppress T cell responses?

Answer 6

CD4 regulatory T cells

Question 7

What interacts with MHC presented antigens, is an incidence detector, is similar structurally to immunoglobulins but only bind amino acid sequences and defines T cells?

Answer 7

T Cell Receptors

Question 8

Which class of T cell receptor is the “Classic”, is involved in adaptive immunity, is common in the circulation (not tissues), develops and matures in the thymus and undergoes positive and negative selection?

Answer 8

α:β T cell receptors

*T cells only express 1 class. δ chain genes are embedded within the α chain genes

Question 9

Which class of T cell receptor is not involved in classic adaptive immunity, monitors tissue health, is found in tissues (not circulation) develops but does not mature in the thymus, and has limited positive and negative selection?

Answer 9

γ:δ T cells

*T cells only express 1 class. δ chain genes are embedded within the α chain genes

Question 10

Which chain has the V,J,C segments and has junctional diversity?

Answer 10

α Chain

*3 hypervariable/complementarity-determining regions per chain. RAG 1/2 complexes

Question 11

Which chain has the V,J,D,C segments and has junctional diversity?

Answer 11

β Chain

*3 hypervariable/complementarity-determining regions per chain. RAG 1/2 complexes

Question 12

What complex do TCRs require for signal transduction?

Answer 12

CD3 complexes

*TCR plasma membrane expression does not occur without the CD3 complex

Question 13

What do Major histocompatibility complexes (MHCs) present?

Answer 13

They present antigens to TCRs

Question 14

Which class of MHC presents intracellular antigen, is expressed on all cells, ER antigen loading, binds the CD8 co-receptor and has an α chain and β2 micro globulin

Answer 14

MHC class 1

*All MHC are associated with Human Leukocyte Antigen (HLA) complex

Question 15

Which class of MHC presents internalized antigen, is expressed on antigen presenting cells, binds CD4 co-receptor, is a vesicular ER loader and has α and β chains?

Answer 15

MHC class II

*All MHC are associated with Human Leukocyte Antigen (HLA) complex

Question 16

In the ER, which protein stabilizes the Class I heavy chain until β2M binds?

Answer 16

Calnexin

Question 17

In the ER what 4 proteins make up the peptide-loading complex with the class I heavy chain and β2m?

Answer 17

1-clareticulin
2-tapasin
3-TAP (delivers the peptide to form the mature MHC I)
4-ERp57

Question 18

When the peptide loaded on to MHC I is too long, which enzyme removes N-terminal AAs to give a 8-10 residue peptide?

Answer 18

ERAP

Question 19

The invariant chain blocks the binding or peptides to MHC II in the ER and is then cleaved in vesicles leaving what?

Answer 19

CLIP fragment which blocks binding of peptides in vesicles

Question 20

What protein facilitates release of CLIP from MHC II?

Answer 20

HLA-DM

Question 21

CD8 binds what domain of the MHC I?

Answer 21

α3 domain

Question 22

CD4 binds what domain of the MHC II?

Answer 22

β2 domain

Question 23

Developing T cells within the thymus are called what?

Answer 23

Thymocytes

Question 24

Which T cells maintain tissue integrity, do not express CD4 or CD4 co-receptors and interact with non-classical receptors?

Answer 24

γδ T cells

Question 25

Which T cells are helper T cells, have several types, regulate adaptive and innate immune function and interact with MHC Class II?

Answer 25

CD4 T cells *MHC class II typically on Dendritic cells, B cells and macrophages (antigen presenters)

Question 26

Which T cells are cytotoxic T cells, have direct effector function and interact with MHC class I?

Answer 26

CD8 T cells

Question 27

The thymus is the site of all T cell development. Selection of thymocytes occurs as they move in what direction?

Answer 27

From Cortex to medulla *TCR development within the cortex

Question 28

What happens to the thymus with age?

Answer 28

It involutes (gets smaller) *CD4 half life=4.2 yr CD8= 6.5 yr

Question 29

Stem cell surface marker CD34 and Adhesion CD44 are present in what stage of T cell development?

Answer 29

Uncommitted progenitor cell (prior to reaching thymus)

Question 30

CD2 and CD5 adhesion/signaling proteins along with IL-7 cytokine receptor and CD1A (MHC class I-like molecule) are found in what stage of T cell development?

Answer 30

Double-negative thymocyte committed to the T-cell lineage *TCR has begun to rearrange

Question 31

What molecule is a T Cell transcription factor involved in T cell arrival to thymus?

Answer 31

Notch1

Question 32

Which molecule is a B cell transcription factor?

Answer 32

Pax-5

Question 33

What are the 3 major stages of T cell development?

Answer 33

1-Double-negative 2-Double-positive 3-Single-positive

Question 34

What are the four stages of the double-negative stage?

Answer 34

1-Committed T cell progenitor 2-Rearrange β,γ,δ (mainly β) 3-First checkpoint (Pre-TCR) 4-Proliferating pre-T cells (has pTα as surrogate α chain)

Question 35

What are the two stages of the double-positive stage?

Answer 35

1-Rearrange α (if γ,δ has not formed) | 2-Second checkpoint (has both CD8 and CD4, positive and negative selection take place)

Question 36

What happens then the γ or δ gene rearrangement takes place?

Answer 36

Suppressed the β and α * β, γ, δ, rearrangement are first. γ:δ cells leave the thymus with little selection.

Question 37

β-chain production drives what?

Answer 37

CD4 and CD8 expression (double positive)

Question 38

How many attempts are made to achieve the productive rearrangement of the β-chain locus?

Answer 38

Four attempts (two attempts per locus, two genes)

Question 39

B-chain rearrangement forms a Pre-T cell receptor, and is the first checkpoint. It must then bind what and assemble what to then drive the signal forward?

Answer 39

- Must bind pTα (surrogate α-chain analogue) - Assembles the CD3 complex *forms a super dimer

Question 40

What three things does the formation of the CD3 complex and passing the 1st checkpoint drive?

Answer 40

1-Halts Rag funtion 2-Proliferation 3-Expression of CD4 and CD8

Question 41

What is eliminated when the α-chain is rearranged?

Answer 41

The γ:δ locus thus excluding γ:δ cells. *Prior to rearrangment, cell can still develop into γ:δ

Question 42

What are the 5 major genes that are expressed during T cell development?

Answer 42

``` 1-Notch 2-Kit/stem cell factor (SCF) 3-RAG 4-CD3 5-IL-7 ```

Question 43

What are the 4 stages of development as the T cells move from the sub-capsular region toward the medulla?

Answer 43

1-Proliferation and differentiation to double-positive CD3+ thymocytes (sub-capsular cortex) 2-Positive selection (cortex) 3-Negative selection (corticomedulary junction) 4-Entry to the circulation (medulla)

Question 44

Ensuring that the MHC is bound by cortical epithelial cells presenting self-peptides on MHC I/II in the thymusis the second checkpoint and is called what?

Answer 44

Positive selection *TCR must bind mHC within 3-4 days. a-chain may rearrange but once bound it turns off RAG 1/2

Question 45

What process determines CD4 or CD8 expression and requires co-signaling?

Answer 45

Positive selection *CD4 binds MHC II and CD8 binds MHC I

Question 46

What process prevents self-antigen binding through the use of centric cells and macrophages presenting self-peptides to create central tolerance?

Answer 46

Negative selection *peripheral tolerance may also occur. Naive mature T cells can still undergo differentiation

Question 47

Once a Mature, naive T cell is formed, where does it go?

Answer 47

Blood stream or lymph system