T cells

Question 1

What does CD stand for?

Answer 1

cluster determinant

Question 2

What are CD4 T cells?

Answer 2

helper t cells

Question 3

What are CD8 T cells?

Answer 3

cytotoxic T cells

Question 4

What do CD4 T cells do?

Answer 4

orchestrate immune response

Question 5

What do CD8 T cells do?

Answer 5

recognise infected cells and kill them

Question 6

How are T cells produced?

Answer 6

• precursor produced in bone marrow
• during gestation they migrate from bone marrow to thymus

Question 7

Describe the structure of a T cell receptor?

Answer 7

• constant region interacts with lymphocyte
• variable region interacts with antigen

Question 8

How are the variable regions of T cell receptors produced?

Answer 8

• just like antibodies
• somatic recombination between T cell receptor gene segments

Question 9

What presents the peptides rom antigens to the T cells?

Answer 9

• antigen presenting cells
• by major histocompability (HMC) molecules

Question 10

What is the class I pathway for antigen presentation?

Answer 10

1. virally infected cell is synthesising viral proteins
2. these pass through ER and golgi into cytoplasm
3. a sample of the proteins passed into the proteasome
4. proteins are degraded into peptides and returned to ER by TAP transporter
5. in ER, peptides are loaded onto MHCI molecules

Question 11

What is the proteasome?

Answer 11

tubular organelle lined with enzymes

Question 12

How do CD4 T cells differ from CD8 t cells when it comes to processing peptide antigens?

Answer 12

• antigen is presented by MHC Class II molecules
• antigen only presented by specialised antigen presenting cells
• antigen is taken up from extracellular space

Question 13

What is the Class II pathway for antigen presentation?

Answer 13

1. macrophages and dendritic cells sample antigens from extracellular space by endocytosis
2. antigens degraded into peptides and loaded onto MHCII

Question 14

How are B cells involved in antigen presentation by Class II pathway?

Answer 14

they can only present antigens that bind to their antibody receptor

Question 15

How do CD4 T cells help with B cell maturation?

Answer 15

• once B cell presented antigen to T cell, T cell provides signal to B cells via cytokines and juxtacrine signalling

Question 16

How do T cells differ from B cells in their clonal selection?

Answer 16

• very similar, make loads and pick the best one
• however T cells do not mutate their receptors like B cells