Lecture 4 Flashcards

(25 cards)

1
Q

How long does the adaptive system responce last for

A

Days - Weeks

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2
Q

Does does the adaptive immune responce carry out recognition

A

Via antigen : antigen receptros

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3
Q

Where are B and T cell produced

A

Bone marrow

  • B cells mature in bone marrow
  • T cells mature in the thymus
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4
Q

What are the 2 types of T-cells

A
  • CD4+ T cells - regulate immune system
  • CD8+ T cells - kill virally infected cell bodies
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5
Q

That is the difference between PAMPS and Antigens

A
  1. PAMPs
  • ​Non specific recognition
  • Limmited number of PAMPS that are common to many different pathogens
  1. 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
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6
Q

What is the B cell antigen receptor - BCR

A

Memebrane bound antibody - IgG/IgD

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7
Q

Explain the T cell antigen receptor

A

Membrane bound alpha,Beta Heterodiamer

  • Alpha chain
  • Beta chain
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8
Q

Describe antibodies

A
  • 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
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9
Q

Desctibe the structure of antibodies

A
  • 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
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10
Q

Why can antibodies have different reachs

A

Flexible at hinge

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11
Q

How can different antibodies exist if they have the same structure

A

Have different Ig heavy chain regions

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12
Q

What are the different types of heavy chains and antibodies

A

*

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13
Q

Which part of the antibody is the antigen binding site

A

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

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14
Q

Describe the TCR and its binding site for antigens

A
  • Membrane bound heterodimer of alpha and beta chains
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15
Q

How can the immune cell recognise millions of different antigens

A
  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
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16
Q

T and B cells elimination of pathogen process

17
Q

Where does the adaptive immue responce occur

A

Secondary lymphoid tissue

18
Q

How do nieve B and T cells enter lymph nodes

A

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
Q

How do antigens enter the lymph nodes?

A
  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
Q

How are T cells activated

A
  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
Q

Describe the two classes of MHC molecules

A
  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
Q

What are the 2 signals required for T-cell activation

A
  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
Q

Whats the function of stromal cells in B-zones

A

Trap opsonised antigens

24
Q

How do B-cells get activated

A

they dont need to be presented with MHC peptide

25
What happens to activates B and T cells