INF Year 2 TB1 > Week 1 > Flashcards

Week 1 Flashcards

Introduction to immunity and defecnce against infection (85 cards)

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1
Q

Define Variolation

A

Early method of immunization specifically using material from skin wounds of small pox

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2
Q

When and where is variolation first recorded?

A

1400s in Middle East/ China

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3
Q

What year does the WHO say smallpox was eradicated?

A

1980

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4
Q

Who is the father of vaccination?

A

Edward Jenner

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5
Q

What is an antigen?

A

Refers to any substance recognised by the immune system

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6
Q

Give examples of live/ nonlive antigens

A

Proteins, Glycoproteins, Polysaccharides of pathogens
Metals eg. nickel
Penicillin
Poison ivy (urushiol)

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7
Q

What kind of cell produces immunoglobulins?

A

Differentiated B cells (plasma cells)

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8
Q

Define antiserum

A

Fluid component of an immune person’s clotted blood that is used for vaccination

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9
Q

What are the two sections of an antibody?

A

Fab and Fc

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10
Q

Describe the Fab section of an antibody?

A

Fragment Antigen Binding
(Antigen specificity area- variable region)
Made up of 2 light chains

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11
Q

Describe the Fc section of an antibody?

A

Fragment Crystalised
Constant Region
Made up of 2 heavy chains

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12
Q

How are the Fab and Fc regions joined in an antibody?

A

Disulphide bond

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13
Q

What are the three main functions of an antibody?

A

Neutralization
Opsonization
Complement Activation

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14
Q

Describe Neutralization via an antibody

A

-Stops bacterial toxins binding to cell surface receptors, allowing macrophages to digest
-via binding of Fc portion of antibody binding to Fc receptor on macrophage
eg. tetanus

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15
Q

Describe Opsonization via an antibody

A

-Bacteria in extracellular space
-Antibodies coat bacterial surface
-Fc receptors bind to macrophages
-Promotes ingestion and phagocytosis

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16
Q

Describe Complement Activation via an antibody

A

-Antibodies coat bacteria
-Fc binds complement proteins
-Causes lysis or ingestion

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17
Q

What is complement?

A

A set of plasmsa proteins that act agains pathogens in extracellular space that either kill or mark out for phagocytosis. Activated via 3 pathways

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18
Q

Is the Innate immune response specific or non specific?

A

non specific

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19
Q

Is the adaptive immune response specific or non specific?

A

specific

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20
Q

Similarities and differences between humoral and cellular responses?

A

Both are adaptive immune responses.
Humoral= B cells and antibodies
Cellular= T helper and T killer

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21
Q

What are the 7 key elements of the innate immune response?

A
  1. Physical barriers
  2. secreted components
  3. proteolytic enzymes
  4. complement cascade
  5. ion chelators
  6. interferons
  7. Macrophages/ neutrophils
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22
Q

What branch of immune response is most important in early infection vs later infection?

A

Early= innate
Later=adaptive

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23
Q

What anatomical/ physical barriers does the human body possess?

A
  1. strong= hair, skin, nails
  2. weak= more vulnerable mucosal surfaces
  3. mechanical= airflow, cilia and coughing
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24
Q

What chemical barriers does the human body possess?

A
  1. Skin fatty acids
  2. Lysozyme in saliva, sweat and tears
  3. Pepsin in gut
  4. pH (stomach. vagina)
  5. antibacterial peptides (cryptidins made by paneth cells in GI disrupt bacterial membranes)
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25
What microbiological barriers does the human body possess?
Normal biota competes with 'dangerous' for nutrients, space. eg. lactoferrin, lactobacillus crispatus ferments glycogen from vaginal cells creating lactic acid, lowering pH, inhibiting pathogen growth
26
What complement/ antimicrobiological proteins does the human body possess?
C3, defensins, Reg III Gamma (helps defend the gut from bacterial infections. It is an antimicrobial peptide that binds to and neutralizes Gram-positive bacteria,)
27
How is the immune system activated?
1. Inflammatory inducers 2. Sensor cells 3. Mediators 4. Target tissues
28
What Inflammatory inducers activate the immune system?
Bacterial LPS ATP Urate crystals
29
What sensor cells help to activate the immune system?
Macrophages neutrophils Dendritic cells
30
What cells help to mediate the immune system?
Cytokines Cytotoxicity
31
What kind of stem cells do all blood cells arise from?
Pluripotent hematopoietic
32
What do common lymphoid progenitor cells become?
White blood cells Innate lymphoid cells Natural killer cells T/B lymphocytes
33
What do common myeloid progenitor cells become?
Granulocyte Macorphage Megakaryocyte Erythrocyte
34
What is a granulocyte?
Precursor of mast cells. named due to grainy appearance. Can become neutrophil, eosinophil,basophil, monocyte
35
Which progenitor cells do dendritic cells come from?
Both myeloid and lymphoid
36
What are a macrophages role?
Phagocytosis Becateriacidal mechanism activation Antigen presentation cytokine and chemokine production
37
What is a neutrophils role?
Phagocytosis Bacteriacidal mechanism activation NETs modultate adaptive immunity
38
What is a dendritic cells role?
Immature= antigen uptake Mature=antigen presentation in lymph nodes
39
What is a eosinophils role?
Fighting big pathogens (parasitic worms) Immune regulation Metabolic regulation (adipose and insulin)
40
What is a basophil role?
Inflammation and histamine release Helminth worms= TH2 immune response Bridge adaptive and innate with IL2
41
What is a mast cell role?
Allerigic responses via heparin, histamine and cytokines
42
Where do B cells mature?
Formed and mature in the bone marrow
43
Where do T cells form and mature?
Form= bone marrow Mature=Thymus
44
What happens when a T cell recognises a HLA (Human Leukocyte Antigen aka MHC)?
Differentiation into effector T cells
45
Why are T cell subsets named starting with 'CD'?
Cluster of Differentiation Theyre defined by the cluster of antibodies that can indicate a differentation stage
46
What do CD4 T cells do and what do they recognise?
Helper (supporting B cells) Cytokine production Class II HLA is recognised
47
What do CD8 T cells do and what do they recognise?
Cytotoxic Class I HLA is recognised
48
Describe a Class I HLA
Transmembrane alpha chain (alphas 1,2,3) Contains the peptide binding site between alpha folds Beta Microglobulin chain
49
Describe a Class II HLA
Heterodimer (alpha and beta chain) alpha 1+2, beta 1+2 Peptide binding site in between a and b
50
What is different about the peptide binding groove in Class II compared to Class I?
Highly polymorphic, can bind a high variety of peptides, and much longer peptides than Class I
51
What are the three stages of T cell response?
1. Naive T cell (lymph nodes help them meet. precursor frequency is 1/100,000) 2. Expansion (10^5 fold) 3. Contraction (leaves behind memory precursors)
52
What makes a T cell likely to become a memory cell?
chemokine receptors IL7 and IL15
53
Describe a Professional Antigen Presenting Cell (APC)
Stimulates naive T cells Presents antigens on cell surfaces post ingestion Expresses costimulatory molecules on surface
54
How do B and T cells recognise antigens in different ways?
B= B cell receptors/antibodies recognise native antibodies T= recognise a fragment of antigen presented by an MHC molecule
55
What is an epitope?
Amino acid sequence which is a portion of the antigen that is bound to the antibody
56
What are the generative/ central lymphoid organs?
Bone marrow, Thymus Lymphoid development
57
What are the peripheral lymphoid organs?
Spleen, lymph nodes, mucosal associated Accure- interaction of lymphocytes with an antigen
58
How does the lymphatic system work?
Collects antigens from peripheral organs, brings to thoracic duct, returns lymph to blood
59
how is the structure of the lymph node important for function?
Capsule and trabeculae: A fibrous capsule surrounds the node, and trabeculae (capsular extensions) extend into the node, providing structural support and creating pathways that guide the flow of lymph through different compartments. Cortex: This outer layer contains B cell follicles. After a B cell encounters an antigen, it can proliferate and mature in a "germinal center" within the follicle, a structure formed in response to an infection. Paracortex: Located beneath the cortex, this area is primarily populated by T cells and dendritic cells. It is a crucial site for T cells to interact with antigens presented by dendritic cells, initiating a T cell-mediated immune response. Medulla: The innermost region of the node contains a high concentration of plasma cells, which are B cells that have been activated and are now actively secreting antibodies to fight the infection. Vessels: Lymph enters through afferent vessels and exits through efferent vessels. The flow path allows the fluid to be filtered and for immune cells to be exposed to foreign particles as they pass through the node. Sinuses: Macrophages are located within the sinuses of the lymph node, where they can engulf and destroy foreign particles and pathogens from the lymph as it travels through.
60
If an infection is located in thy cytoplasm, what immune cells would fight it?
Cytotoxic T cells NK cells
61
If an infection is located in the vesicle, what immune cells would fight it?
Macrophages activated via T and NK cells
62
If an infection is located in interstitial space, blood or lymph, how would immune cells would fight it?
Antibodies, complement, phagocytosis, neutralization
63
If an infection is located on epithelial surfaces, what immune cells would fight it?
Antibodies (especially IgA) and antimicrobial peptides
64
Name the three goals of complement
1. Recruit inflammatory cells 2.opsonization of pathogens 3. killing of pathogens
65
Where are complement proteins made?
Liver
66
Complement proteins are zymogens, Define zymogen
Initially inactive, must be cleaved/ activated especially
67
C3 is spontaneously cleaved at a very low rate into what?
C3a (short soluble) C3b (rapidly covalently binds to bacterial cell membrane)
68
Describe the alternative pathway of complement activation
1. C3b binds to microbial surface via thioester bond 2. B binds C3b and changes shape 3. Factor D binds B and cleaves B 4. Factor D leaves, Ba falls off
69
After the 4th step of the alternative pathway, C3bBb is left. What is this?
a C3 convertase so more C3bBb means more C3 convertase positive feedback causes tickover rate to increase
70
What happens when lots of C3b associates with Bb?
Acts as a C5 convertase
71
Describe MBL structure
Triple collagen helices Triple alpha helical coiled coils Trimeric clusters of carbohydrate recognition domains (in MBLs) Or Fibronectin domains (in ficolins)
72
What does Masp stand for?
MBL associated serine proteases
73
What residues do MBL bind to?
Mannose Fucose
74
What do ficolin bind?
Oligosaccharides containing acetylated sugars
75
Which MASP bind to MBL vs Ficolin?
MBL= MASP 1,2,3 bind Ficolin= MASP 1,2 bind
76
Which proteins of the complement are cleaved by MASP 1+2?
C4 C2
77
What is C4bC2a?
C3 convertase
78
What is C4bC2aC3b?
C5 convertase
79
What are the roles of C3a and C5a?
-Peptide mediator of inflammation -Phagocyte recruitment
80
What is the role of C3b?
Binds to complement receptors on phagocytes-> opsonization and removal
81
Which are the terminal complement components?
C5b C6, C7, C8, C9
82
What do the terminal compleemtn components form?
Membrane Attack Complex
83
How does the MAC form?
1. C5bC6C7 binds to pathogen lipid bilayer 2. C8 binds and crosses membrane 3.C9 binds and inserts onto membrane 4. 1-16 molecules of C9 to form a pore into the membrane
84
What kind of infection does a C3 defect cause?
Pus forming (pyogenic) [staph and strep] Highlights the importance of C3 in opsonization
85
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