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MMED 2935 > Immune response and bacteiral infection > Flashcards

Immune response and bacteiral infection Flashcards

1
Q

Describe:

Antigen

A

Specific immune target, immune system sees epitote on antigen to make response

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2
Q

Describe:

Pathogen defence levels

A

First line: physical barriers (acids, membranes)
Second line: innate immune system (immediate cell response, destroy pathogen and release cytokines)
Third line: adaptive immune system (B and T cells)

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3
Q

Describe:

Cytokines

A

Signal messenger sent from macrophage / neutrophil signaling immune response

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4
Q

Describe:

Innate response

A

Present all life, general response, no memory, fast.

Phylogenic, fungi parasites

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5
Q

Describe:

Innate mucosal surface response to specific pathogens

A

Barrier protection can cause infection without symptoms
Respiratory cilia:
Measles, influenza, hemophilic influenzas, CoV-2
GI tract cilia:
Rotavirus, salmonella, clostridium difficle

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6
Q

Describe:

Innate immune cell location

A

Exists in cells, when infected it moves into mucous

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7
Q

Describe:

Innate immune cells in respiratory tract

A 
Macrophage (resident): 
Mast cell (basophil in blood)
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8
Q

Describe:

Macrophage

A

Antigen presenting cell, cytokine release cell, releases chemo-attractants.
Phagocytose microbes

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9
Q

Describe:

Macrophage phagociticprocess :

A

Recognition via surface receptor
Phagocytosis, formation of phagosome
Digestion by lysosome with enzyme and production of presentation peptides (dendritic cells)
Killing of microbes (neutrophils)
Killing can be assisted by NO or reactive oxygen species (ROS)

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10
Q

Describe:

Mast cells

A

Acute innate cells, called basophils in circulation
Contains histamine, degranulates through stimulation.
Acts on vessel,Histamine constricts smooth muscle and dilates blood vessels(immune response).

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11
Q

Describe:

Detection of pathogens by innate cells:

A

Pathogen-associated molecular patterns PAMPs
Pattern-recognition receptors recept general classes of microbes.
[toll-like receptors TLR / Scavenger receptor

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12
Q

Describe:

Toll like receptors

A

Trans membrane receptors (outer and inner membranes)
TLR, recognise PAMPs
TLR 4 recepts LPS (lipopolysaccharides)
Exists internally and externally on innate immune cells

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13
Q

Describe:

Types of cytokines

A

Lymphocyte activation IL-6
Chemotactic, attracts immune cells (eukocytes/lymphocytes)
NK call activator

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14
Q

Describe:

Local vascular response to bacterial infection

A

TLR / scavenger receptors on innate immune cell hit bacteria, causes release of cytokine, chemokine.
Increases vasodilation and vascular permeability.
Inflammatory cells migrate into tissue from blood, releasing inflammatory mediators.

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15
Q

Describe:

Recruitment of immune cells from blood

A

Cytokines cause permeability / dilation, slowing blood flow, immune cells marginalise to edges. Cytokines cause immune cells to have more affinity to vessel proteins.
Once stuck to wall they move out of blood through diapedesis.
Immune cells follow concentration of chemokines

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16
Q

Describe:

Neutrophil

A

White blood cell
Kills bacteria / fungi via phagocytosis
Rapidly recruited from blood (shot lived)
Replaced by macrophages in late stage.
Dead neutrophils cause pus, bad in respiratory

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17
Q

Describe:

Dendritic cells

A

6+ hour from infection
Pro phagocytic cell (APC)
Induces innate immune cell activity (NK cells)
Involved in initiation of adaptive immune response
Migrates to lymphoid tissue after contact with infection, presents antigen to T and B cells.

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18
Q

Describe:

Natural killer cell

A

NK cell, kills cells via granzyme and perdorin. Either inhibitory or activating.
Identifies targes based on missing self (non self or damaged)
Inhibitory signal comes from recognition of I MHC = no response
Activating signal comes from binding to ligand with not inhibitory binding, or viral particles, causing apoptosis.

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19
Q

Describe:

Innate immune contributors activation

A

Serum proteins formed in liver circulate inactive.
Activated though:
Classical, antibody bound pathogen (C1q)
Mannose-Lectin, repeated polysaccharide
Alternative, foreign structure motif (C3b)
This process cascades from one activated protein

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20
Q

Describe:

Innate immune contributor action

A

Serum proteins formed in liver circulate inactive.
Activated though:
Classical, antibody bound pathogen (C1q)
Mannose-Lectin, repeated polysaccharide
Alternative, foreign structure motif (C3b)
This process cascades from one activated protein

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21
Q

Describe:

Innate immune contributor action

A

Recruitment of inflammatory cells
Opsonization; coating of target
Killing of pathogens via chemotaxis (movement / activation) then lysis (membrane attack complex enters membrane)

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22
Q

Describe:

C-reactive protein

A

CRP

Acute phase protein, increases with inflammatory process, good medical indicator.

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23
Q

Describe:

Granulocyte Macrophage Colony stimulating factors

A

GM-CSF, G-CSF
Releases by immune cells causing bone cells to divide and increasing white blood cells when circulating neutrophils are depleted. Over time immature neutrophils will appear in blood and show that there has be a time of infection.

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24
Q

Describe:

Proinflammatory Cytokines

A

TNF-a, IL-1,6,8

Elicit inflammatory response

25
Q

Describe:

Immunocompromised

A

Damage to immune response

Innate: damage to cilia or goblet cells

26
Q

Describe:

Adaptive immune response specificity

A

Immunoglobin (Ig) receptors medicate reception

When recognised B or T cell goes through clonal selection

27
Q

Describe:

Fever purpose

A

Body moves away from bad temperatures which can make a less habitable environment for bacteria, slowing down replication of pathogen

28
Q

Describe:

Pain in joins from immune response

A

Cytokines are transported around body having influence around body causing inflammation. Increases fluid in joints causing pressure of nerves.

29
Q

Describe:

Nausea from immune response

A

Gut is sensitive to cytokines in blood

30
Q

Describe:

Lymphocyte cell formation

A

Pro b/t cell made in bone marrow
Surface immunoglobulin receptor (BCR) made during maturation
Finds way to lymph nodes after maturation

31
Q

Describe:

Formation of immunoglobulin receptor

A

Initially forms heavy chains (2)
Then light chains (2)
Only B/T cells with weak antigen recognition survive into mature cells

32
Q

Describe:

Immunoglobulin structure

A 
BCR has constant region (Fragment constant) of lower half of heavy chains
Variable region (F ab) has upper half of heavy chains and 2 light chains
33
Q

Describe:

Genes of BCR

A

B cell receptors (immunoglobulin)
Many variable, differentiate, joining genes for chromosome of heavy chains in DNA
Mature B cell has only 1 of each gene from DNA via recombination by RAG-1/2 protein
Gives variation, occurs in both heavy and light chain in Ig molecule

34
Q

Describe:

Risk in BCR diversity

A

Some may become self reactive
Must be removed before autoimmunity occurs via tolerance
High affinity BCR recognition can be apoptosed in bone marrow or go through receptor editing to become non reactive or anergic

35
Q

Describe:

B cell clonal division

A

Naive cell’s BCR notices antigen becomes active and divides
Without T-cells: plasma cells, produce antibody IgM
With T-cells: IgG expressing B cell -> isotype switching
High affinity Ig-expressing B cell -> memory B cell or high affinity IgG secretion

36
Q

Describe:

Lymph node availability

A

Samples infection site
Cells move from blood into tissue, into lymph back into blood
B cells can activate when target comes through lymph node

37
Q

Describe:

BCR crosslinking and signaling

A

Activation requires multiple signal event
BCR should cross link (2 receptors are pulled together by target)
Brings phosphorylation cascade together
Can also occur through BCR and compliment receptor activation or toll like receptor

38
Q

Describe:

Conjugation of B and T cells in lymph node during activation

A

B cells in the outer secondary follicle move to margin of follicle
T cells in the inner medulla move to margin of follicle
Increasing chance of B and T cell binding through up regulation of molecules

39
Q

Describe:

B cell antigen presentation

A 
B cell endocytoses carrier epitope, processes it and presents antigen on class 2 MHC complex for activated CD4 T cell to recognize. 
The epitope presented does not have to be the same as the epitope recognized by BCR
40
Q

Describe:

Cognate T cell help

A

After helper T cell detects MHC, B cells’ surface molecules are recepted and T cell releases cytokines causing class switching resulting in memory.

41
Q

Describe:

Class switching in b cells

A

Constant region of BCR changes, IgM changes to IgG or IgA via constant region gene

42
Q

Describe:

Formation of germinal centre

A

Activated B cell proliferates in germinal centre over weeks
Mutations occurs and high affinity B cells are selected (can bind better to follicular dendritic cell)
Selected cells form memory / plasma cells

43
Q

Describe:

Affinty maturation of B cells

A

Complementary determining regions (CDRs) can mutate over years resulting in higher affinty antibody

44
Q

Describe:

Thymus dependant B cell activation

A

T cell help for B cells only works with proteins and thus affinity maturation is unavailible for shugars and nucleic acids
Memory is limited

45
Q

Describe:

Secondary Ig response

A

Is much higher with IgG due to affinty maturation.

IgM does not have this effect

46
Q

Describe:

Antibody purpose

A

Can class switch (forms IgM/A/G)
Fc receptors on phagocytes (NK cells) can eat cell with antibodies attached
Compliment acitvation, allos inflammation, lysis of microbes and phagocytosis with compliment fragments

47
Q

Describe:

Antibody mediated effector mechanisms

A

Opsonization = deposition

Neutralization =holding and linking, prevents entry through barriers

48
Q

Describe:

Adaptive immune response in baby

A

IgG antibodies cross placenta from blood, IgG and IgA contained in breast milk

49
Q

Describe:

GI tract antibodies

A

IgA plasma cell in lamina propria forms dimeric IgA, endocytosed into mucosal epithelia as complex with poly Ig receptor, secreted into lumed as IgA

50
Q

Describe:

Effector function of Ig classes

A 
IgG = opsonization for phagocytosis
IgM = opsonization for activation of compliments
IgA = mucosal immunity, post-neonate immunity
IgE = mast cell degranulation (hypersensitive reactions)
51
Q

Describe:

Generation of T cell variation

A

Constant and variable region of T cell with alpha and beta chains

52
Q

Describe:

T cell formation

A 
Formed in bone marrow (CD4, CD8, TCR)
Matured in thymus and selected to specialize
Specialise in medulla (CD8 [class 1], CD4 [class 2]lymphocyte, Treg)
53
Q

Describe:

T cell entry into thymus

A

Enter through cortical regions (forms surface receptors)

Move into medullary region

54
Q

Describe:

Positive selection of T cell maturation

A 
Pre mature T cells are both CD4 [class 2] and CD8 [class 1], positively selected for low affinity recognition of MHC
Low affinity desired so that several sources will cause a response
55
Q

Describe:

Negative selection of T cell maturation

A

Medullary thymic epithelial cells test for self reactive T cell
AIRE in medullary cell can form different peptides associated with other body cells
Causes apotosis or diversion to Treg cell

56
Q

Describe:

T cell maturation

A

Dendritic cells eat pathogen and present on MHC with costimulation to naïve T cell [Class 2] forming effector T cells

57
Q

Describe:

Class 2 and class 1 MHC pathways

A

Class 1: viral, self peptides

Class 2: phagocytosed peptides

58
Q

Describe:

Immune tolerance

A

APC can phagocytose body cells with virus, presents both virus and body on MHC
Treg notices this and shuts it down turing it back to antinflamitory

59
Q

Describe:

Role of activated T cells

A

CD4 helper : B cell differentication, macrophace activation
CD8 CTL; kills microbe infected cells and tumor cells
CD4 regulatory: suppress T cell function

MMED 2935 (3 decks)

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