Exam 1: L13

Question 1

How is the concept of every person having their own fingerprint like T cell antigen receptors?

Answer 1

• T cells are monospecific
• each T cell have antigen receptors that are identical
• each TCR will bind the same MHC peptide ligand

Question 2

Suppressive T helper cell2 (Th2)
- produces?
-function?

Answer 2

• Produces: IL 3, IL 4, IL5
  Function:
• IL3 and IL 4- help B cells in class switching
  -IL 4 dampens inflammatory cell responses

Question 3

Inflammatory T helper cell 1 (Th1)
- produces?
-function?

Answer 3

produces: gamma interferon and IL-2
function: produces them to activate macrophages, T cells, and NK cells

Question 4

Inflammatory T helper cell2 (Th17)
- produces?
-function?

Answer 4

produces: IL 17, IL21, IL 22
Function: IL 17- Stimulates many innate immune system cells and non-immune cells to synthesize cytokines IL-1, IL-6, and TNF (tumor necrosis factor)

Question 5

Regulatory T cells (Tregs)
- types?
- produces?
-function?

Answer 5

• natural T regs- derived from thymus
• Induced T regs- developed in the periphery from naive T cells in the presence of TGF beta.
• function: inhibit the differentiation and function of the other subsets of CD4 T cells

Question 6

What signals activate the T cell ?
- first ? second?

Answer 6

-first signal: TCR complex binding to MHC I or MHC II;
- Components of TCR: CD3, Zeta/zeta or zeta/ eta, with ITAM on it

• second signal: CD 28 (co-stimulation) binding to B7.1/B7.2 on APC

Question 7

How can you turn off a T cell?

Answer 7

• CTLA-4 bind with B7.1/B7.2
• CTLA-4 has a stronger affinity to B7 than CD28
• homologous to CD28

Question 8

What are other molecules in T cell surface?

Answer 8

• L- selectin
• integrins–> LFA-1 and VLA- 4

Question 9

what are the functions of CD3 and zeta?

Answer 9

• transduction of activation signals in through serial phosphorylation of signal molecules by ITAM sequences on CD3 and zeta (short tail of TCR)
• Cd3 is required fir assembly and transport of the TCR to the cytoplasmic membrane
• TCR and CD3 are mutually dependent; mutation is one abrogate expression of the other

Question 10

What is the function of CD4?

Answer 10

• enhances (by 100 fold) the binding of alpha/beta TCR to peptide MHC-II ligand to invariant site on beta 2 domain of MHC-II molecule
• brings the tyrosine kinase lck (adaptor molecule) closer to the TCR for signal transduction

Question 11

What is the function of CD8?

Answer 11

• enhances binding of TCR to peptide MHC-I TO THE INVARIANT SITE ON ALPHA 3 domain of the MHC-II
  -hence bring the tyrosine kinase lck closer to TCR for signal transduction

Question 12

What happens if only 1 signal is delivered and no signal 2?

Answer 12

Anergy