1.3 Lymphocyte development

Which cells do lymphocytes descend from?

Marrow pluripotent haematopoietic stem cells

Which cells are MHC 1 molecules on and why?

All nucleated cells- can all be infected by viruses

Which cells are MHC 2 molecules on and why?

Antigen presenting cells (dendritic cells, macrophages, B cells)- present antigens to TH cells

Describe the structure of an antibody and what genes code for what. (4)

• Light chain variable region- V/J

• Light chain constant region- C

• Heavy chain variable region- V/D/J

• Heavy chain constant region- C

Describe the structure of a TCR and what genes code for what. (4)

• Alpha chain variable region- V/J

• Alpha chain constant region- C

• Beta chain variable region- V/D/J

• Beta chain constant region- C

What is the purpose of VDJ recombination?

Ensures many combination possibilities for binding diversity in antibodies/TCR

Which region of which immune cells undergo somatic mutations?

V regions of activated B cells

Which substance drives VDJ rearrangement?

IL7

List a way to artificially stimulate somatic mutation for antigen driven diversity.

Injection of antigens via vaccination

What are the 2 ways (aside from VDJ recombination) in which antigen driven diversity occurs?

Somatic mutation and class switching

Why are equine SCID sufferers immunocompromised?

Deficient in DNA dependent protein kinase causes lack of VDJ recombination

Describe the 4 steps of T cell development and where each occurs in the thymus.

• Lineage commitment- subcapsular

• TCR gene rearrangement (VDJ)- cortex

• Proliferation and expansion- medulla

• Selection- cortex

Name 2 ways in which the thymic epithelial cells provide instructions for T cell maturation.

• Cell to cell contact

• Soluble factor production

Which MHC presents antigens to which T cell?

• MHC1- CD8

• MHC2- CD4

What are ‘nude’ mice and why are they good for research?

• Lack thymus so cannot make T cells

• Immunocompromised and so cannot react to foreign material/transplants

List the 3 different degrees of interaction affinities in T cells during selection and why (or why not) they are selected.

• Low interaction affinity- cannot bind to MHC and so die by neglect

• Appropriate interaction affinity- positive selection

• High interaction affinity- negative selection, bind too strongly to self protein which may be harmful