immunology

Question 1

how does the skin contribute to preventing infection

Answer 1

composed of tight keratinised cells that are, has a low pH and O2 tension, secretes hydrophobic oils, lysozyme and antimicrobial peptides

Question 2

how does mucous prevent against infection

Answer 2

lines body cavities in line with outside world (GI tract), traps bacteria, secretes antibodies

Question 3

how do commensal bacteria prevent against infection

Answer 3

symbiotic with host, compete with fatty acids, produce toxins to other bacteria

Question 4

describe the nature of the innate immune system

Answer 4

fast, non adaptive present since birth

Question 5

what are the cells involved in the innate immune system

Answer 5

Macrophages, dendritic cells, NK cells, mast cells (neutrophils basophils, eosinophils)

Question 6

what is the inflammatory response

Answer 6

increases body temp and attracts macrophages

Question 7

describe the nature of adaptive immunity

Answer 7

slow, specific, from memory

Question 8

describe macrophages

Answer 8

pink cytoplasm and kidney bean nucleus, develop from circulating monocytes, they phagocyte cells, reside in tissues, monocytes are precursors

Question 9

describe dendritic cells

Answer 9

present in large numbers in tissues, are professional antigen presenting cells to T cells, phagocytes

Question 10

describe natural killer cells

Answer 10

release cytotoxic molecules that kill infected cells by apoptosis, respond to MCH I

Question 11

describe mast cells

Answer 11

reside in tissues, single nucleus, fight antibody-coated parasites, illicit inflammatory response by degranulation (histamine, TNF, IL)

Question 12

how do innate immune cells recognise pathogens

Answer 12

pathogens express PAMPs and immune cells have receptors for his PRRs

Question 13

what is the main function of phagocytosis, what are the main cells

Answer 13

to ingest and kill cells/ bacteria/ fungi. macrophages, neutrophils and dendritic cells

Question 14

describe how phagocytosis works (up until debris release)

Answer 14

PRR recognises PAMPs, creates phagosome around target. fuses with lyososme (contains ROS) and kills pathogen, debris is released to EXC space

Question 15

how do phagocytes ‘remember’ antigens

Answer 15

peptides from antigen are expressed on cell surface receptors MCH II

Question 16

what else is released after phagocytosis

Answer 16

pro-inflammatory mediators TNFa

Question 17

describe opsonisation

Answer 17

coating of pathogens in opsonins to aid phagocytosis

Question 18

name some major opsonins

Answer 18

C3b, Fc of IgG, CRP

Question 19

what happens to virally infected cells

Answer 19

release interferons (INFa/b), NKC’s can recognise

Question 20

what happens when large parasites are present

Answer 20

too large to be phagocytosed, results in degranulation - pro inflammatory substances eg IFNy

Question 21

what are the 5 types of leukocytes (WBC’s)

Answer 21

neutrophils, eosinophils, basophils, monocytes, lymphocytes

Question 22

what are neutrophils for

Answer 22

initiation and upkeep of inflammation

Question 23

what are the steps of transendothelial migration

Answer 23

margination of neutrophils to endothelium, bind to adhesion molecules and pass across endothelial by diapedesis. attracted to site of injury by chemotaxis, activated by PAMPs and TNFa

Question 24

neutrophils kill pathogens in what 3 ways and what do they release

Answer 24

phagocytosis, degranulation, NETs - TNF when activated

Question 25

how do neutrophils kill by phagocytosis

Answer 25

pathogens release chemokines, phagolysosomal or ROS-dependent killing which requires NADPJ

Question 26

how do neutrophils kill by degranulation

Answer 26

release of anti-bacterial protein

Question 27

how do neutrophils kill by NETs

Answer 27

activated neutrophils release intracellular structures that immobilise pathogens and facilitate phagocytosis

Question 28

what is the acute phase response of innate immunity

Answer 28

liver releases proteins in response to pro-inflammatory mediators eg . (interleukines and TNF)

Question 29

what proteins does the liver release

Answer 29

CRP, compliment proteins: C4, C3, C2

Question 30

what is the complement system

Answer 30

creates a cascade reaction in response to inflammation and infected cells

Question 31

what are the 3 complement pathways

Answer 31

classic, alternate, lectin

Question 32

what is the classic complement pathway

Answer 32

antibodies cause conformational change in C1 which activates C3 --> C3a + C3b

Question 33

what is the alternative pathway

Answer 33

C3b is unstable and so rapidly degreades back to C3 unless it binds, cells express inhibitory proteins to prevent C3b activated downstream events

Question 34

what are the 3 components of the downstream compliment system

Answer 34

MAC, opsonisation, inflammation

Question 35

what proteins make the MAC complex

Answer 35

C5-C9

Question 36

what sequence of events activates MAC

Answer 36

C3b activates C5 --> C5a and C5b. C5b activates MAC

Question 37

what is the function of C3a and C5a

Answer 37

attract macrophages for phagocytosis and are inflammatory mediators

Question 38

what do cytokines

Answer 38

produced in response to inflammation/ infection and regulate cell behaviour for immune system

Question 39

name some pro-inflammatory cytokines

Answer 39

TNF, interleukins

Question 40

what do interferons do

Answer 40

viral infections

Question 41

what do chemokines do

Answer 41

control cell migration

Question 42

which cells are involved in acquired immunity

Answer 42

B cells and T cells

Question 43

which is humoral

Answer 43

B cells

Question 44

where are B cells developed

Answer 44

bone marrow

Question 45

where are T cells produced

Answer 45

thymus

Question 46

where is primary lymphoid tissue

Answer 46

bone marrow and thymus

Question 47

where is secondary lymphoid tissue

Answer 47

spleen, tonsils, lymph nodes

Question 48

what are antigens

Answer 48

specific structures on pathogens which allows them to be identifies

Question 49

what do B cells produce and what are they

Answer 49

antibodies specific to antigens, are Y shaped glycoproteins and act as opsins

Question 50

what are the immunoglobins produces in the blood from most to least abundant

Answer 50

IgG, IgA, IgM, IgD, IgE

Question 51

where do T and B cells become activated

Answer 51

secondary lymphoid tissue

Question 52

how do T and B cells enter the lymph node

Answer 52

transendothelial migration from high endothelial venules (HEV)

Question 53

Once B cells are activated what happens

Answer 53

they clonally proliferate and differentiate to different cells: effector plasma cells (produce antibodies) or memory cells

Question 54

what does IgG do

Answer 54

antibody immunity to developing foetus

Question 55

what does IgA do

Answer 55

secretory: found in breast milk, blood, mucosal defense

Question 56

what does IgM do

Answer 56

found in blood, first antibody produces

Question 57

what does IgD do

Answer 57

unknown

Question 58

what does IgE do

Answer 58

activates mast cells to cause degranulation (allergic response)

Question 59

What cells produce MHC I and what do they present to

Answer 59

all nucleated cells, CD8+T cells

Question 60

What cells produce MHC II and what do they present to

Answer 60

antigen presenting cells: dendritic, macrophages, B cells,. | activate CD4+T

Question 61

what can CD4+T differentiate into

Answer 61

TH0, TH1, TFH

Question 62

what does CD4+T release to cause it to differentiate into TH0, where does this occur

Answer 62

IL2, lymph nodes

Question 63

What does TH0 differentiate into and what does this do

Answer 63

TH1, leaves lymph nodes and goes to inflamed tissue

Question 64

what does TFH do

Answer 64

activates B cells in germinal centre of lymph nodes

Question 65

what does CD8+ develop into

Answer 65

killing cells: cytotoxic T lymphocytes

Question 66

how does CTL kill cells

Answer 66

migrates out of lymph nodes and binds to infected cells, inserts DNA for apoptosis.

Question 67

what can activate B cells

Answer 67

IL4, Il5, IFNy

Question 68

what do mast cells and basophils do

Answer 68

secrete inflammatory stuff eg histamine in allergic reaction

Question 69

what is the lectin pathway

Answer 69

mannose binding lectin imitates C1 and activates C3