T Lymphocytes

Question 1

4 steps of T cell diversity and selection in the thymus

Answer 1

1. Proliferation (Increased number of T cell progenitors)
2. TCR gene rearrangement
3. Positive selection
4. Negative selection

Question 2

Positive selection of T cells

Answer 2

Makes sure that the TCR can bind to MHC

Happens in the cortex

Question 3

Negative selection of T cells

Answer 3

TCRs that react too strongly to MHC are eliminated

Happens in the medulla

Question 4

Structure of the TCR

Answer 4

Alpha chain and Beta chain

Each with a constant region at the bottom, and a variable region at the top

Question 5

Is there more B cells, more T cells, or equal numbers?

Answer 5

More T cells

Question 6

What is SCID

Answer 6

Severe Combined Immunodeficiency Disorder

The failure to make a TCR

Question 7

TREC

Answer 7

T cell receptor excision circle
As the genes come together to make a TCR, bit are left out
In the cell it forms a TREC
Presence of them indicates mature T cells

Question 8

How are T cells activated

Answer 8

Recognition of antigen in MHC

Costimulation by APCs in lymphoid organs

Question 9

2 main inhibitory receptors of T cells

Answer 9

CTLA-4

PD-1

Question 10

Where does CTLA-4 work

Answer 10

Inhibits T cells at initial priming stage

In the Lymphoid organs

Question 11

Where does PD-1 work

Answer 11

Inhibits activated T cells

In the periphery

Question 12

Function of effector CD4 cells (2)

Answer 12

Activation of macrophages, B cells, and other cells

Inflammation

Question 13

Function of effector CD8 cells (2)

Answer 13

Killing of infected cells

Macrophage activation

Question 14

What co-stimulation molecule is found

1. On T cells
2. On APCs

Answer 14

1. CD28

2. B7