T CELLS

Question 1

TCR1

Answer 1

5% of T cells
Gamma and delta chains
Mucose protection and against virus
Non-classical MHC recognition

Question 2

TCR2

Answer 2

95%
Interaction with classical MHCs
Alpha and beta chains
Present in CD4 & CD8

Question 3

CD3

Answer 3

Formed by alpha, epsilon and delta chains
Universal marker for T cells
Covalently bound to alpha and beta chains of TCR2

Question 4

Z chain

Answer 4

9 Aa homodimer related to intracellular functions

Question 5

Signal transduction on T cells

Answer 5

Phosphorylation of ITAMs present in Z chain
Interaction of ITAMs with different proteins
Activation of transcription factors
Expression of IL-2 and its receptor and other cytokines

Question 6

NK CD

Answer 6

CD16
CD56
CD94

Question 7

NK characteristics and main functions

Answer 7

Cytotoxic abilities without previous immunisation required
ADCC / Indirect cytotoxicity
Natural cytotoxicity / Direct cytotoxicity
Defence against IC pathogens
Recognition of CD1

Question 8

Functions of T cells accessory molecules

Answer 8

1. Binding of T cells to APCs, endothelial cells and extracellular matrix
2. Regulate lymphocytes responses
3. Can be used as markers

Question 9

T accessory molecules positive signals

Answer 9

CD40/CD40L

B7-CD28

Question 10

T accessory molecules negative signals

Answer 10

B7-CTLA4 (=CD152)

Question 11

CD4

Answer 11

Interaction with MHC-II (exogenous pathway) via beta chain of the peptide binding side

Question 12

CD8

Answer 12

Dimer.

Interaction with MHC-I (endogenous pathway) via alpha2

Question 13

Functions of CD8 and CD4

Answer 13

1. Antigen recognition
2. Signal transduction by lck tyrosine kinase
3. Adhesion to cells
4. Receptors for VIH (Dx by counting CD4+ molecules)

Question 14

CD28

Answer 14

Activation of naïve T cells

Bind to CD80 (B7) and CD86 in APCs

Question 15

CTLA-4 (CD152)

Answer 15

Inhibition of T cell activation
ITIMs
Recrution of kinase in charge of phosphorylation
Higher affinity for CD80 and CD86 than CD28

Question 16

CD45

Answer 16

Present in different isoforms of T cells

Activaiton of Lck

Question 17

CD2

Answer 17

Expressed in mature T cells and NK cells

Adhesion and signalling molecule

Question 18

Adhesion molecules

Answer 18

Integrins and selectins

Question 19

Integrins

Answer 19

Binds to other cells or ECM
Combination of different alpha and beta chains. Heterodimer
Adhesion of T cells to APCs, endothelial cells and ECM

Question 20

Selectins

Answer 20

Enables binding of platelets and leukocytes to sugars
L-selectins: CD62L (lymphocytes and leukocytes)
E-selectins: CD62E (endothelial cells)
P-selectins: CD62P (platelets)

Question 21

Events taking place in T cell ontogeny

Answer 21

Generation of T cells
Positive selection (destruction of the ones that can’t interact with MHCs)
Negative selection (destruction of the ones interacting with self-antigens)

Question 22

Cells resulting from T cell ontogeny

Answer 22

T helper cells
T cells
T regulatory cells

Question 23

Maturation of T cells

Answer 23

IL-7 induced

1. Pre-timic phase
2. Thymic phase I,II and III
3. TdT and Rag enzymes cut and paste different chains necessary for maturation

Question 24

Pre-thymic phase

Answer 24

Pro-T cells

There are no T cell markers expressed nor receptors

Question 25

Thymic phase I

Answer 25

``` Pre-T cells // Double negative cells CD2+ and TdT+ Rearrangement in beta chain of TCRs that associated to CD3 or Z chain Signals expression that allow: - Rearrangement of alpha chain in TCR - Stimulation of CD4 and CD8 coreceptors - Proliferation - Allelic exclusion ```

Question 26

Thymic phase II

Answer 26

Inmature T cells // Double + CD2+, CD3+, CD4+ and CD8+ 95% die (+ selection) Phenotypical maturation associated to functional maturation

Question 27

Thymic phase III

Answer 27

Mature T cells // Single + CD2+ , CD3+ and CD4/CD8+ Negative selection

Question 28

AIRE

Answer 28

Transcription factor that allows the expression of tissue specific antigens in the thymus to allow the negative selection of mature T cells

Question 29

Gene recombination and expression of antigen receptors

Answer 29

Expression of TCRs | Parallel to maturation process