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MMI > Innate Immune Response > Flashcards

Innate Immune Response Flashcards

1
Q

What are the 3 main components in first line innate immune response?

A
  1. Skin
  2. Mucous membranes and Secretion
  3. Normal Flora
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2
Q

What are the 4 main components in second line innate immune response?

A
  1. innate immune cells
  2. inflammation
  3. complement
  4. antimicrobial substances
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3
Q

What are mucous membranes

A

thin and permeable barriers that line the respiratory, GI and genitourinary tracts

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4
Q

What is technical removal

A
  • the two components involved are the ciliated cells and mucous secretions
  • produces a ciliary escalator –> dust particles sitting on the mucous membrane will be pushed either down the digestive tract or up through the airways and out of the lungs by movement of cilia underneath
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5
Q

4 types of secretions

A
  1. Tears, Saliva (contains lysozyme that breaks down peptidoglycan - can eat away gram + and - layer)
  2. Crevicular Fluid (fluid that flows into gingival crevice - has similar composition to blood serum)
  3. Gastric juices (have low pH)
  4. Urine/Vaginal Secretions (have flushing action, and maintain a certain level of pH)
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6
Q

What is the normal flora in the mouth

A

Alpha streptococci

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7
Q

what is the normal flora on the skin

A

staphylococcus epidermidis

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8
Q

what is the normal flora in the lower GI

A

bacteroids spp. (aerobic gram neg)

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9
Q

What composes an inflammatory response

A

SHARP

Swelling
Heat
Altered function
Redness
Pain
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10
Q

what is pus?

A

mixture of dead cells, neutrophils and body fluid

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11
Q

what is an abscess?

A

accumulation of pus (pustules and boils are examples)

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12
Q

what are pyogenic bacteria? what are two examples?

A

pyogenic bacteria are pus causing bacteria (causes pus production)

  • streptococcus pyogenes
  • staphylococcus aureus
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13
Q

5 types of white blood cells?

A
  1. Granulocytes (PMNL - polymorphonuclear leukocytes) –> four types: neutrophils, basophils, eosinophils, and mast cells
  2. Monocytes –> White blood cells in the blood stream that are travelling to the infectious tissue
  3. Macrophages
  4. Dendritic Cells –> stay in skin
  5. Natural Killer Cells (destroy infected host cell, intracellular bacteria, virus or cancer cells) but does not kill bacteria directly, it just kills the host cell; it looks like a lymphocyte and attacks any organism without prior knowledge or exposure
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14
Q

What are polymorphonuclear leukocytes? what do they have?

A

PMNL are granulocytes (type of WBC) that differentiates into:

  1. Neutrophils
  2. Basophils
  3. Eosinophils
  4. Mast cells
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15
Q

What is hematopoiesis

A

the process of blood cells differentiating from stem cells in the bone marrow

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16
Q

What are neutrophils?

A
  • 60 to 70% of total WBC (most amount)
  • able to phagocytose
  • short life span, no mitochondria (less than a day)
  • first to arrive and initiate phagocytosis at infected site
  • forms NETs when they die (sticky DNA that traps bacteria and makes it easy for other neutrophils to eat it in large amounts)
  • have vacuoles with granules that have anti-microbial proteins and inflammatory mediators
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17
Q

What do the granules of neutrophils have?

A

myeloperoxidase (turns pus green) and superoxide radicals (oxygen radicals that kill organisms)

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18
Q

What are macrophages?

A
  • 3 to 8% of total WBC
  • very efficient phagocytes
  • eats damaged cells like dead neutrophils
  • is an antigen presenting cell
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19
Q

what are macrophages called in blood circulation?

A

monocytes

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20
Q

what are macrophages called in tissue?

A

macrophage

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21
Q

Antigen Presenting Cell

A

cells that can break down infectious pathogens and present its parts on the cell surface

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22
Q

what are dendritic cells

A
  • efficient antigen presenting cell
  • phagocyte
  • activates adaptive immunity (specific response)
  • carries the antigen from infected tissue to lymph glands where the T and B lymphocytes live and presents it to them to help them remember what it is
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23
Q

What are eosinophils

A
  • provides defence against PARASITIC infection
  • secretes cytolytic enzymes upon contact with pathogens (causes cells to burst)
  • cells circulate in the blood until recruited to inflamed tissue
  • they secrete enzymes to break down the cuticle of parasites
  • increased eosinophils in the blood indicate a parasitic infection (the start of one)
24
Q

What are mast cells?

A
  • mostly in submucosal tissues
  • cell surface receptor for igE (immunoglobulin E)
  • important in allergic reactions
  • releases histamine once the igE is activated
25
Q

What are basophils?

A
  • found in blood
  • similar function to mast cells
  • release histamine from their granules
26
Q

What are two types of leukocyte granules?

A
  1. Lytic granules (contain digestive enzymes like lysozyme to breakdown endocytose pathogens
  2. Secretory granules
    - kills pathogens that are too big to eat like parasites, - contain chemical messenger substances that attract other immune cells to the site like chemokines
    - have inflammatory mediators like histamine
27
Q

What are Natural Killer Cells (NK)

A
  • lymphocytes without memory but live in our lymph gland
  • first line of defence against intracellular pathogens (viral infections, intracellular bacteria/protozoa, and cancer cells)
  • secrete cytolytic granules that cause targeted cell destruction
28
Q

which 3 cell types do NK cells destroy?

A
  1. infected cells –> when there’s a microbial antigen present on MHC 1
  2. Virally infected cells which have lost the expression of MHC 1 on the surface
  3. Cancer cells that have LOST MHC 1 in general (dont even have it)
29
Q

What is MHC Class 1?

A
  • receptor thats on the surface of normal nucleated cells (NOT ON RBC BECAUSE THEY DONT HAVE NUCLEUS)
  • Healthy cells present a self protein that is bound in the MHC 1
  • sick cells (virus or cancer) may have a foreign peptide in the MHC 1
30
Q

what is the role of MHC 1?

A

provides a way for cytotoxic T cells to scan and detect intracellular infection (third line - adaptive immunity)
and NK cells detect the cells that are not showing self-peptides and kill them
- presents endogenous peptides (peptides made by the own cell either by a virus or the healthy cell itself
- activates CD8+ cytotoxic cells

31
Q

what are MHC 1 receptors called in humans?

A

HLA (Human Leukocyte Antigen)

32
Q

What is MHC class 2?

A
  • it is the receptor that found ONLY on ANTIGEN PRESENTING CELLS (I.E. macrophages, dendritic cells and B-lymphocytes)
  • Bind and presents the antigen (peptides) to t-helper cells in order to initiate adaptive immune response
  • presents exogenous peptides (peptides made outside the cell like fragments of bacteria that was phagocytosed)
  • activates CD4+ t-helper cells
33
Q

what is phagocytosis?

A

when a cell engulfs a solid particle

34
Q

what is diapedesis?

A

the migration of cells across the endothelium through the cell junctions (how cells get from blood vessel to tissue site)

35
Q

what is chemotaxis?

A

the directed movement of cells in a concentration gradient (substances emitted by bacteria that WBC can sniff out)

36
Q

What are the 7 steps of phagocytosis by Antigen Presenting Cells?

A
  1. bacterium binds to the receptor on phagocyte
  2. Phagocytosis - bacterium is engulfed by cell membrane
  3. Bacterium inside the cell vesicle (phagosome)
  4. fusion of lytic granule (like lysosome) and phagosome forming a phagolysosome
  5. digestion of bacterium by lysosomal enzymes
  6. transport of bacterial fragments to cell surface (binds to the MHC 2 receptor on the phagocyte)
  7. release of waste material
37
Q

Cytokines

A

small proteins that are made by cells, that function to change or communicate with other cells (cause us to have a fever)

38
Q

What are two types of Cytokines?

A
  1. chemokines –> cytokines that are used for attracting other cells to the site of infection (proteins made by WBC that cause a chemical signal)
  2. interleukins –> cytokines that alter the function of other cells
39
Q

What are Pattern Recognition Receptors and whats an example?

A

PRR’s are receptors on the inside or outside of a cell that recognize parts of foreign cells

and example is the toll Like Receptor (TLR) which recognizes different molecules from pathogens
i.e. the outer TLR’s recognized Lipopolysaccharide, peptidoglycan and flagellin while the inner TLRs detect RNA and DNA

40
Q

What 3 things happen after a TLR is triggered by a foreign molecule?

A
  1. Chemokine release: calls in help from the circulation
  2. Proinflammatory cytokine release: activates neighbouring cells (cells around the endangered cell) and helps with cell signalling
  3. increased microbicidal activity: destroys the ingested pathogen
41
Q

Antigen

A

a substance that is usually foreign, that is capable of producing an immune response (i.e. virus, bacteria, protozoa, pollen and transplanted tissue)

42
Q

Epitope

A

the specific site on an antigen thats recognized by immune cells or antibodies

43
Q

antibody

A

also called immunoglobulin (Ig)
- protein produced by B-lymphocytes that recognizes a specific epitope on an antigen –> this leads to removal of that antigen

44
Q

What is the complement system and how is it activated?

A

the complement system is a group of serum proteins (liquid part of blood) produced by the liver in the circulation to defend against pathogens

the complement immune reaction occurs on the surface of the cell and punches a hole in bacterial cell wall and it explodes

45
Q

what are the three complement pathways?

A
  1. classical
  2. alternative
  3. Lectin
46
Q

What is the classical complement pathway?

A
  • triggered by antibody-antigen complex (antibody binds to epitope on antigen)
  • Then, C1 breaks into C2 and C4
    C2 and C4 break into C2a and C2b as well as C4a and C4b
    C2a and C4a make C3 which splits into C3a and C3b,

c3b makes c5 which splits into c5a and c5b

then c5b joins with c6 + c7 + c8 + c9 to form the membrane attack complex (MAC)

47
Q

what is the alternative pathway?

A
  • triggered y lipid-carbohydrates (LPS) which is just C3 splitting into c3a and c3b and then c3b going to make c5 which splits into c5a and c5b and c5b goes to join with C6-9 to form MAC
48
Q

what is the lectin pathway?

A

triggered by mannose and results in formation of MAC complex as well

49
Q

What is the role of c3b in the complement pathways?

A

c3b is an opsonin and is involved in opsonization –> attracting phagocytes to the pathogen; this coats the bacteria and phagocytes have a c3b receptor to find it

50
Q

what is the role of c3a and c5a?

A

ANAPHYLATOXINS –> mast cell degranulation (i.e. releasing histamine from mast cells) which mediates inflammation

51
Q

what is the role of c5a alone?

A

chemoattractant to leukocytes (WBC) [recruits phagocytes, this is chemical not cytokines]

52
Q

what is the role of c5b, c6, c7, c8, and c9?

A

they form the MAC (membrane attack complex) which bores a hole in the outer membrane of the pathogen

53
Q

what are interferons (IFN)?

A

type of cytokine (cell signalling)
- produced by virally activated cells [released by host cells in response to certain viruses]
- defence molecule against viruses
(causes nearby cells to heighten antiviral defence)

54
Q

antimicrobial peptides (AMPs)? [2 types]

A
  • production is triggered by activation of toll-like receptors (binding to foreign pathogen parts)
  • broad spectrum antibiotic that destabilizes membranes of gram + and - bacteria as well as fungi and enveloped viruses
  • two types:
  • dermcidin: produced by sweat glands
  • defensives: produced by neutrophils and macrophages
55
Q

C-reactive protein (CRP)

A

C-reactive protein CRP is an acute phase protein (protein that increases or decreases in plasma content) that marks BACTERIA for enhanced phagocytosis (opsonization)
it is produced in the liver during infection

increased levels of CRP indicate a bacterial infection/inflammation

this is important in paediatrics as babies cant tell you the symptoms of a bacterial infection but increase CRP in their blood stream tells you they are dealing with it and they have an infection

56
Q

Why is innate immunity important?

A
  • its the first response to invasion by pathogens and it doesnt need to be primed
  • it holds the fort until the adaptive system is ready to help out
  • continues to help with defencing even when the adaptive system is initiated (OVERLAPPING)
  • has a large degree of redundancy in case one branch is defective

MMI (18 decks)

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