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MICR 270 > module 3 > Flashcards

module 3 Flashcards

1
Q

what is the adaptive immune response ?

A

second line of defence when the innate immune response is not enough , known as being antigen specific

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2
Q

what are the 5 phases of the adaptive immune response ?

A

antigen recognition, lymphocyte activation, elimination of pathogens , contraction, memory

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3
Q

antigen recognition

A
  • NEED to identify and activate cells from adaptive immunity that recognize antigens . PAMPs are seen by APCs like dendritic cells and macrophages - APC will present antigen to naive T cell via MHC complex proteins
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4
Q

Lymphocyte activation

A
  • this step is used to produce a large quantity of immune cells specific to the pathogen
    requires a series of cellular interactions leading to T cell and B cell differentiation and clonal expansion
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5
Q

elimination of pathogen

A
  • step is used to completely destroy pathogen where humoral and cell mediated immunity are used
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6
Q

contraction

A

Majority of lymphocytes will undergo apoptosis after removal of pathogen. vast majority of immune cells will die becasue they can cause more harm than good in the body

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7
Q

Memory

A

establishment of immunological memory, the few adaptive immune cells that remain will become memory cells -ability to produce fast immune response if reinfected

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8
Q

why is antigen presentation needed ?

A

adaptive immune system has specific immune cells capable of recognizing a specific antigen , presentation is needed to identify which cells should be activated

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9
Q

What is the MHC ?

A

serves as a self label, which helps recognize and identify self from non self molecules to make sure the immune system wont attack the host

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10
Q

role of MHC molecules

A

display antigenic peptides on the surface of cells, which can be recognized by the TCR and co receptors ( CD4 and CD8) to initiate adaptive immune response

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11
Q

what are the different classes of MHC molecules and why are they needed ?

A

MHC class 1 and MHC class 2
which help distinguish between the different recognition patterns

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12
Q

what is the role of Antigen presenting cells ?( APC )

A

They are needed because T cells cannot recognize pathogens themselves . An APC will internalize a pathogen by either phagocytosis or receptor mediated endocytosis where peptides ( antigens will be presented on the MHC on the cell surface which will be recognized by T cells

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13
Q

professional APCs

A

Macrophages, B cells , dendritic cells –> These cells are the most efficient in presenting antigens to MHC class 2 and will send cositmodulatory signals to activate T cells

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14
Q

non profESSIONAL APCs

A

fibroblasts and glial cells - can be induced to express MHC 2 but normally they dont ( in sustained inflammatory responses ).

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15
Q

antigens are processed to form what effective peptide?

A

MHC singalling complex , there are 2 pathways to form this

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16
Q

Pathways to form MHC signalling complex

A

endogenous and exogenous pathways

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17
Q

endogenous pathway

A

formation of MHC complex 1 that is recognized by CD+8 cytotoxic T cells

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18
Q

exogenous pathway

A

formation of MHC complex 2 recognized by CD4+ helper T cells

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19
Q

role of endogenous pathway

A

cell will be able to process self and foreign particles and present them at surface to be recognized by T cell receptors on cytotoxic T cells

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20
Q

what are the 5 steps in the exogenous antigen processing ?

A

antigen engulfment, proteolytic processing, formation of MHC antigen complex, cell surface expression, recognition by helper T cell

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21
Q

What is antigen engulfment ?

A

macrophages, B cells and dendritic cells engulf foreign antigen by endocytosis forming an endosome

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22
Q

what is proteolytic processing ?

A

foreign antigens inside endosome are broken down into fragments by proteolytic processing (Protease cleaves bonds in one or more proteins ).

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23
Q

formation of MHC antigen complex

A

vesicle with foreign fragments will fuse with vesicles containing MHC molecules( from ER). creating MHC antigen complexes

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24
Q

Cell surface expression

A

MHC antigen complex is transported to the plasma membrane where it will be displayed on the surface of the cell

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25
Q

recognition by helper T cell

A

TCR will bind to MHC antigen complex on the cell surface of APC to initiate adaptive immune response

26
Q

B cell receptors

A

B cell receptors needed for antigen recognition which will have a membrane bound antibody and signal transduction molecules- they will recognize and bind to pathogens directly

27
Q

T cell receptors

A

made up of membrane bound antigen specific molecule and signal transduction molecules (CD3 and ITAMS )

28
Q

CD4 co receptors are expressed on

A

Helper T cells and will recognize peptide MHC class 2 complex

29
Q

CD8 co receptors are expressed on

A

Cytotoxic T cells which will recognize peptide MHC class 1

30
Q

what are cytokine networks

A

coordinate immune responses and modulate balance between the humoral and cell mediated immunity

31
Q

4 classes of cytokines

A

chemokines, interleukins, interferons , tumour necrosis factor and growth factor

32
Q

what is lymphocyte activation ?

A

interactions with many immune cells which will mediate a specific immune response

33
Q

why is the interaction between B cells and T cells important ?

A

interactions will induce the exchange of activation signals between the 2 lymphocytes allowing strong humoral immune response

34
Q

3 signals leading to B cell activation

A

1) TCR- peptide : MHC complex
2) co stimulation ( B7:CD28, CD 40: CD40L )
3) cytokines

35
Q

step 1 in B cell activation

A

antigen binds to BCR, on B cell, if signal is not string enough to activate cell , antigen will be internalized by receptor mediated endocytosis and will be displayed on the membrane of the MHC

36
Q

STEP 2 in B cell activation

A

Specific TCR complex and CD4 co receptor on the T cell recognizes

37
Q

Step 3 in B cell activation

A

expression of co stimulatory molecules , where signal 1 will induce the expression of CD40L on the cell surface of the helper T cell

38
Q

step 4 B cell activation

A

CD40L and CD28 will bind to CD40 and B 7 expressed on the B cell creating a costimodulatory signal in both cells

39
Q

Step 4 B cell activation

A

known as signal 3 , activated helper T cell ill secrete cytokines which will bind to cytokine receptors

40
Q

what do the 3 signals cause ?

A

stimulate the proliferation and differentiaton of B cells into plasma cells and memory B cells causing the humoral response against a specific antigen

41
Q

interaction between T cell and APC will form what ?

A

immune synapse

42
Q

what is an immune synapse

A

made of signal molecules and adhesion proteins

43
Q

3 components of an immune response

A

signal molecules, adhesion molecules, signal regulation molecules

44
Q

signal molecules ( cSMAC)

A

Has the molecules needed for signalling between 2 cells like TCR and Peptide: MHC molecules

45
Q

adhesion molecules (pSMAC)

A

has adhesion proteins such as integrins and cytoskeletal protein linkers needed to keep all cells in contact long enough for signal propogation

46
Q

signal regulation molecules (dSMAC)

A

proteins containing larger extracellular domains that regulate signal transduction

47
Q

why is an immune synapse needed ?( 4 things )

A
  • activation of T cell
  • hold signal proteins together longer to form stronger connections , allowing proper signal to be produced
  • synapse allows for reorganization inside the T cell which will release of cytokines close to target cell
  • synapse regulates lymphocyte activation
48
Q

what would happen if immune cell activation was incomplete ?

A

down regulation of an immune response preventing T cell proliferation and development of anergic phenotype

49
Q

why are cytokines needed ? what are they used for ?

A

they are chemical messengers that are secreted by immune cells needed for cell to cell communication and needed to regulate immune function

50
Q

types of cytokines

A

chemokines, interleukin, interferons , tumour necrosis factor, growth factor

51
Q

chemokines function

A

induce chemotaxis, call in cells to region of infection are needed for wound healing , cell mediated and humoral immune responses , inflammation

52
Q

Interleukins

A

contains 10 sub families , regulate immune and inflammatory responses , primarily effect proliferation and differentiation of immune cells and hematopoietic cells

53
Q

interferons

A

induce antiviral state and inhibit replication of viruses , regulate immune responses

54
Q

Tumor necrosis factor

A

invovled in systemic inflammation, involved in tumor regression, can cause apoptosis

55
Q

Growth factors

A

stimulate growth, proliferation, healing, cell differentiation

56
Q

what is the outcome of B cell activation ?

A

proliferation and differentiation into plasma cells and memory B cells

57
Q

what is immunological memory ?

A

ability for lymphocytes to respond more efficiently to re- infection by previously encountered antigen, where there will be a faster immune response - central feature of adaptive immunity

58
Q

natural passive immunity

A

Short lived immunity (6 months around )
aquired by the fetus from the mother , where there is placental transfer of antibodies in pregnancy and breastfeeding
NO immunological memory

59
Q

artificial passive immunity

A

injection of serum of antibodies , temporary immunity
NO immunological memory

60
Q

Natural active immunity

A

acquired through infection by a pathogen , innate and adaptive immune responses
- high chance of developing immunological memory

61
Q

artificial active immunity

A

vaccination, innate and adaptive and innate immune responses but with no symptoms , High chance of immunological memory development

MICR 270 (2 decks)

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