Unit 2- Development of T & B Cells

Question 1

What do we mean by Variability in T & B Cells?

Answer 1

there are a large number of variable (V) and J gene segments- one V and one J makes a whole variable domain
Variable domain is generated using a different combination of the V and J gene segments

Question 2

What other two things (besides variability in T & B cells) can drive diversity in T & B cells?

Answer 2

1. Somatic Mutation- mechanism for introducing mutations into V regions of activated B cells thereby increasing antibody affinity
2. Class switching- each class has a different biological function

Question 3

How can there be diversity in the T cell receptor?

Answer 3

diversity is focused in the CDR3 region of a T Cell receptor

Question 4

To become a T or B Cell a stem cell needs to _____ _ ______ therefore it undergoes ______ __________

Answer 4

express a receptor

gene rearrangement

Question 5

How does the environment of stem cells lead to the production of B Cells?

Answer 5

the microenvironment (stromal cells) facilitate the development by providing cell to cell interactions

Question 6

Where are blood vessels developed? Which cell differs from this and why?

Answer 6

Bone marrow

Except T cells- developed in the Thymus

Question 7

Briefly describe how T cells are developed in the Thymus?

Answer 7

1. CD4 & CD8 enter the thymus and undergo lineage commitment which is the downregulation of both molecules and then the upregulation of CD4 only
2. T Cell receptors are rearranged so CD8 becomes cytotoxic and CD4 recognise antigens in association with MHC.
3. Proliferation occurs & then the selection of a useful repetoire

Question 8

Which antibody can transfer across the placenta?

Which antibody is present in breast milk?

Answer 8

IgG

IgA