(10) T-cell I

Question 1

read this

Question 2

(2 Classes of T cells)

1. CD8+ cells are what kind of T cells? What do they kill?
2. CD4+ cells are what kind of T cells? activate what? depending on what?

Answer 2

1. cytotoxic T-cells; target cells infected with viruses or display neoplastic (tumorous) antigens bound to MHC class I molecules
2. are inflammatory T cells; activate macrophages, b cells, or neutrophils; pattern of cytokine expression

Question 3

What does CD in CD4 and CD8 stand for?

Answer 3

cluster of differentiation

Question 4

(T cells - antigen specific lymphocytes)

1. Do they recognize foreign antigens only? in the context of what?
2. Do several types of T cells exist?
3. Produced where? educated where?
4. Mature lymphocytes are found throughout the body, but are centralized in what three things?
5. What determines each T cells specificity for a single epitope?
6. Each TCR is associated with either what or what?
7. So whether it is CD4 or CD8 wiil be decided where?
8. Where will what type of CD4 cell be determined?

Answer 4

1. yes; MHC of the same haplotype
2. yes
3. bone marrow; thymus
4. lymph nodes, spleen, and other secondary lymphoid tissue
5. T cell receptor
6. CD4 or CD8
7. thymus
8. in the periphery when it encounters an antigen

Question 5

take a gander at this - think he will go into this stuff in detail so don’t worry about memorizing entire table right now - on ipad

Question 6

(TCR)

1. T cells recognize antigens via what?
2. TCR generates T cell diversity by a mechanism that does what?
3. Are TCR expressed on the T cell surface and secreted?
4. Each T cell expresses 10-30K receptors of identical or different specificity?
5. Does TCR bind antigen in the context of the same MHC molecule (class I or II)?
6. Consists of an antigen specific hetero-dimer of what kinds of chains?
7. The TCR complex is associated with what multi-subunit complex (which is not Ag specific nor variable) but serves to transmit signals if TCR is engaged?

Answer 6

1. the t cell receptor
2. uses somatic recombination of germline DNA
3. only expressed on surface
4. identical
5. yes
6. either alpha/beta or gamma/delta chains
7. CD3

Question 7

look at this

1. What happens to the CD3 molecule?

Answer 7

and this (but don’t memorize!)

1. it gets phosphorylated and sends signal to nucleus

Question 8

1. Are T cell receptor and antibody gene rearrangement similar?
2. What are three regions on the T cell receptor?
3. antigen binding pocket is made up of what?

Answer 8

1. yes
2. constant regions, hinge regions, and variable (antigen) binding regions
3. junction of the alpha and beta chain

Question 9

1. Can collection of all T cell recepotrors theoretically recognize all epitopes?
2. Is it approximately equal to diversity generated by antibodies?
3. Do they have V, D, and J regions?

Answer 9

1. yes
2. yes
3. yes

Question 10

(TCR rearrangement)

1. The alpha chain can choose from how many variable regions? the beta?
2. Rearrangement of gene segments occurs where? gives t-cell receptors a single specificity?
3. Only the TCR from 1 chromosome is expressed - what is this called again?
4. Does any further somatic rearrangement occur once successfully rearranged?
5. So how do T cells differ from antibody molecule in this regard?

Answer 10

1. 100; 30
2. thymus; yes
3. allelic exclusion
4. no
5. no somatic hypermutation, t-cell receptor never secreted

Question 11

Just like antibodies

1. T cells have multiple germ line gene segments
2. binding pocket made up of junction of alpha and beta chain
3. have imprecise joining
4. and random addition of nucleotides

BUT NO SOMATIC HYPERMUTATION

Question 12

(T cell receptor)

1. alpha chains made out of what gene segments?
2. beta chains?
3. Can T cell receptor gene rearrangment occur several times if one rearrangment is non-functional? Is DNA in between lost each time?

Answer 12

1. V and J
2. V, D, and J
3. yes, yes

Question 13

this is a pretty good graph

Question 14

1. Does T cell education in thymus occur in presence of antigen?
2. Is it an antigen-specific immune response?
3. which section of thymus is thicker with T cells trying?

4 where do succesful ones make it and what effect doest his have on appearance?

Answer 14

1. yes
2. no
3. cortex
4. medulla, makes it look lighter

Question 15

1. Does T-cell maturation in the thymus required antigen presentation? What is this referred to as sometimes?
2. What occurs if class I presentation is missing?
3. If they recognize MHc class 1?
4. MHc class 2?

Answer 15

1. yes; educating
2. CD8+ T cells cannot be selected for, an vice-versa
3. only cd8 t cells mature
4. only cd4 t cells mature

Question 16

1. Earliest T cells to enter the thymus are found where?
2. As they mature into double postitive thymocytes - where do they go?
3. What contains only mature, single-positive T-cells which will enter the bloodstream?

Answer 16

1. subcapsular region of the cortex
2. deeper in the cortex
3. the medulla

Question 17

What happens to thymocytes that are able to recognize MHC class 1 or 2 too avidly are what?

what does this accomplish?

Answer 17

• destoryed
• thymocytes capable of responding to self peptide antigens are removed (negative selection or central tolerance)