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Flashcards in Lecture 4 Deck (25):
1

How long does the adaptive system responce last for 

Days - Weeks

2

Does does the adaptive immune responce carry out recognition

Via antigen : antigen receptros 

3

Where are B and T cell produced 

Bone marrow 

  • B cells mature in bone marrow
  • T cells mature in the thymus 

4

What are the 2 types of T-cells 

  • CD4+ T cells - regulate immune system
  • CD8+ T cells - kill virally infected cell bodies 

5

That is the difference between PAMPS and Antigens 

  1. PAMPs
  • ​Non specific recognition 
  • Limmited number of PAMPS that are common to many different pathogens 

    2. Antigens

  • Specific recognition 
  • Millions of different ones that are unique to individual species
  • Individual B and T cells express ony one specific receptor for an antigen 

6

What is the B cell antigen receptor - BCR

Memebrane bound antibody - IgG/IgD 

7

Explain the T cell antigen receptor

Membrane bound alpha,Beta Heterodiamer 

  • Alpha chain 
  • Beta chain 

8

Describe antibodies 

  • Produced by B-cell in responce to an antigen
  • Bind specifically to that antigen
  • Are expressed on surface of B cells and also secreted by B cells as soluble protiens
  • Provide defence againts ectracellular pathogens - Bacteria, viruses and toxins

9

Desctibe the structure of antibodies 

  • 2 Ig heavy chain  and  2 Ig light chain polypeptides held together by disulphide bonds 
  • Each Ig heavy chain and light chain contains: 
  1. Variable region
  2. Constant domaine 

10

Why can antibodies have different reachs 

Flexible at hinge 

11

How can different antibodies exist if they have the same structure

Have different Ig heavy chain regions 

12

What are the different types of heavy chains and antibodies 

  •  

13

Which part of the antibody is the antigen binding site 

Hypervariable regions of Ig light and heavy chains combine to form antigen binding sites

14

Describe the TCR and its binding site for antigens 

  • Membrane bound heterodimer of alpha and beta chains 

15

How can the immune cell recognise millions of different antigens 

  1. B cells -•Antibody heavy and light chain proteins are encoded for by segmented genes in the germ-line genome of haematopoietic stem cells
  • Randome rearrangment in these gene segments occur as B-cells evelop 

    2.  Similar randome rearrangement of TCR a/b chain gene segments occurs in developing T cells

  • Gives rise to hugly direverse B and T cells 
  • This means theres is potential for auto-reactive cells 

16

T and B cells elimination of pathogen process

17

Where does the adaptive immue responce occur 

Secondary lymphoid tissue 

18

How do nieve B and T cells enter lymph nodes

 

Transendothelial migration 

  • Enter lymph nodes from High endothelial venules (HEV)
  • If after several days they dont encounter any pathogen they return back to blood system via Efferent lymphatics 

19

How do antigens enter the lymph nodes?

  1. Debris of pathgens are released by phagocytes 
  2. Inflammatory cytokines (TNFa) stimulate immature, tissue-resident Dendritic Cells ►expression of co-stimulatory molecules
  3. .Dendritic Cells recognise (PAMP:PRR) and phagocytose pathogen-derived particles and antigens
  4. Dendritic cells ingests and display small peptide on surface with a MHC complex 
  5. Pathogen debris, antigens and mature denritic cells move to local draining lymph nodes 
  6. Enter lymphnodes via Afferent lymphatics 

 

20

How are T cells activated 

  1. T cells can only recognise peptide antigens presented to their TCR by MHC molecules 
  2. Also known as HLA molecules - able to present many different peptides 
  3. Encoded by highly polymorphic genes

21

Describe the two classes of MHC molecules 

  1. MHC class 1 - presented on all nucleated cells
  • Present peptide antigens to CD8+ T cells 

​    2.  Class 2 MHC - presented on professional Antigen presenting cells

  • Dendritic cells, macrophages, B cells
  • Present peptide antigens to CD4+ T cells 

    

22

What are the 2 signals required for T-cell activation

  1. Antigen specific stimulation signal 
  • Denritic presents MHC peptides to the TCR of T cellls

    2.  Co-stimulatory signal 

  • B7 molecules : CD28 on T cell 

23

Whats the function of stromal cells in B-zones 

Trap opsonised antigens

24

How do B-cells get activated

they dont need to be presented with MHC peptide 

25

What happens to activates B and T cells