immunology: B & T lymphocyte development

Question 1

What is a leukocyte

Answer 1

WBC

Question 2

What is lymphocytes

Answer 2

A type of WBC, T & B lymphocytes

Question 3

Where is the diversity for antigen binding on B & T cells

Answer 3

Variable region

Question 4

What is VDJ recombination

Answer 4

Genetic process where B & T lymphocytes generate diverse antigen receptors

Question 5

What does HSC divide into first

Answer 5

Common lymphoid progenitor (CLP)

Question 6

What factors ensure that CLP divides into pro-B cells

Answer 6

EBF, E2A & Pax 5

Question 7

What factors ensure that CLP divides into pro-T cells

Answer 7

Notch 1 or GATA3

Question 8

When does CLP become a NK cell

Answer 8

When Notch 1 or GATA3 is absent in T cell lineage

Question 9

Why does lymphocytes have diverse antigen receptors

Answer 9

Recognition of various pathogens

Question 10

How is maturation initiated

Answer 10

Signals from cell surfaces

Question 11

What two processes occur during maturation

Answer 11

1. Promote proliferation of progenitors
2. Initiate rearrangement of antigen receptor genes (VDJ recombination)

Question 12

Where are B cells produced & mature

Answer 12

Bone marrow

Question 13

Where are T cells produced & mature

Answer 13

Produced: bone marrow
Mature: thymus

Question 14

What is the five stages of lymphocyte maturation

Answer 14

1. Commitment of progenitor cell to B-/T cell lineage (signals)
2. Proliferation of progenitors & immature cells
3. Rearrangement/recombination of antigen receptor genes
4. Selection events + & - selection processes
5. Differentiation into different B & T cells

Question 15

What is the two checkpoint present in maturation

Answer 15

1. 1st checkpoint: expresses one chain of antigen receptors (functional heavy chain)
2. 2nd checkpoint: expresses complete antigen receptor (functional light chain)

Question 16

What is positive selection

Answer 16

Survival of potentially useful lymphocytes

Question 17

What is negative selection

Answer 17

Elimination or altering of developing lymphocytes who bind strongly to self antigen

Question 18

What is the process of B cell development

Answer 18

IMAGE

Question 19

What is the three mechanism to modify immunoglobulin gene

Answer 19

1. VDJ recombination
2. Somatic hypermutation
3. Ig heavy chain switch recombination

Question 20

How is the heavy chain compiled

Answer 20

D segment + J segment + V segment in pro-B cells

Question 21

How is the light chain compiled

Answer 21

V segment + J segment in pre-B cells (receptor editing in self-reactive immature B cells)

Question 22

What immunoglobulin does B cell express when leaving bone marrow

Answer 22

IgM

Question 23

What is required for the B cell to mature

Answer 23

Antigen presentation allowing proliferation & differentiation

Question 24

What is receptor editing

Answer 24

Strongly self-reactive immature B cells are induced to make further Ig gene rearrangement to avoid self reactivity

Question 25

What is clonal deletion

Answer 25

If self editing fails & self reactive B cell dies

Question 26

What is the four functions of B cells

Answer 26

1. Antigen presentation 2. Antibody production 3. Memory 4. Inflammation

Question 27

When does proliferation occur in a B cell

Answer 27

1. Stem cell to pro B cell 2. Pre B cell to immature B cell

Question 28

When is RAG expressed in B cell development

Answer 28

1. Pro B cell to pre B cell 2. Pre B cell to immature B cell

Question 29

When does a B cell mount a response to antigen

Answer 29

1. Immature B cell for - selection & receptor editing 2. Mature B cell for proliferation & differentiation

Question 30

When is a T cell double negative

Answer 30

Bone marrow & periphery

Question 31

When does the T cell become double positive

Answer 31

In cortex before positive selection

Question 32

What is positive selection in T cells

Answer 32

Recognition of MHC molecules to express either CD4+ or CD8+ in the cortex of the thymus

Question 33

What is negative selection in T cells

Answer 33

If T cells binds to tightly to self antigen it is eliminated & called **clonal deletion** Mature if binds tightly to foreign antigen

Question 34

What is the three functions of T cells

Answer 34

1. CD8+ T cells + viral infection & **destroy cell** 2. CD4+ T cells + macrophages & release cytokine to activate, release more cytokines & **fight infection** 3. CD4+ T cells + B cell & release cytokines for B cell differentiate into **antibody secreting plasma cells**

Question 35

When is RAG expressed in T cell development

Answer 35

1. pro T cell to pre T cell 2. pre T cell to double + T cell