Innate Immunity

Question 1

Give characteristics of innate immunity

Answer 1

from birth, rapid, no memory

Question 2

What is the function fo pattern recognition?

Answer 2

detect PAMPs, DAMPS and ‘missing self’/natural killer cells

Question 3

Give examples of physical and physiological barriers

Answer 3

physical -skins, mucous membrane

physiological - low pH, body temp, chemical mediators

Question 4

Name the cells of innate immunity

Answer 4

neutrophil, eosinophil, basophil, macrophage, mast cell, dendritic cell, NK cell

Question 5

What are the function of neutrophils, eosinophils and basophils?

Answer 5

neutrophil - phagocytosis and microbe killing
eosinophil - phagocytosis, granule release, help B cell response in gut ALT, defines for parasitic
basophil - granule release, antigen presenting cell for T2 immunity

Question 6

What are the functions of dendritic cells?

Answer 6

antigen capture and presentation, recognise microbial patterns, secret cytokines

Question 7

Compare neutrophils and macrophages

Answer 7

neutrophil - short lives, highly abundant, migrate into tissues, first to infection sit
macrophage - less abundant, resident in tissues, release cytokines to signal infection

Question 8

Summarise the process of neutrophils migrating into tissues (diapedesis and chemotaxis)

Answer 8

roll along endothelium surface
selection ligand binds with low affinity receptor on endothelium
converts integrin to high affinity when chemokines from infection (that are bound to endothelial CSM ) give signal to neutrophil
intergrin binds tightly and neutrophil migrates

Question 9

define opsonisation

Answer 9

coating microorganism with opsonins to facilitate phagocytosis

Question 10

name the neutrophil killing mechanisms and give examples

Answer 10

oxygen independent
-enzymes, lysozyme, antimicrobial peptides
oxygen dependent
-respiratory burst (anions, radicals), nitric oxide

Question 11

What are neutrophil EC traps?

Answer 11

activate neutrophils release granule and chromatin to form EC fibres

Question 12

Summarise macrophage function

Answer 12

express receptor for bacterial constituents
bind to bacteria and release cytokines to initiate response
engulf bacteria

Question 13

Summarise mast cell function

Answer 13

secret histamine granules and inflammatory mediators
vasodilation and increased vascular permeability
recognise and phagocytose bacteria

Question 14

Where are mast cells found and how may they be activated?

Answer 14

lung, skin, peritoneal cavity

anaphylatoxins

Question 15

Summarise the function of NK cells

Answer 15

secrete cytokine interferon-gamma
express activating and inhibitory receptors
express receptors that bind to antibody coated cells (antibody dependant cell mediated cyotoxicity)
lyse target cells

Question 16

Summarise NK target cell recognition

Answer 16

target cells has self recognition molecule on surface which binds to NK inhibitory receptor
infected cell missing self recognition molecule so bids to activation receptor

Question 17

Give the characteristic of cytokines

Answer 17

small proteins, communicate cell-to-cell, act locally, short lived, low concentration required

Question 18

Name the cytokine types and their function

Answer 18

interleukins - between leukocytes
Interferons - antiviral Chemokine - chemotaxis Growth factors - proliferation and differentiation
cytotoxic - tumour necrosis factor

Question 19

What is the purpose of the complement system?

Answer 19

role in complementing the activity of a specific antibody in lysing bacteria

Question 20

Give characteristics of the complement system

Answer 20

triggered enzyme cascade
rapid
components mainly produced in liver

Question 21

Name and describe the 3 ways of activating the complement system

Answer 21

classical pathway - antigen + antibody
lectin pathway - lectin binds to carbohydrate on bacterial surface
alternative pathway - bacterial surface

Question 22

Where do the 3 pathways converge and what is the final stage?

Answer 22

C3b

membrane attack complex

Question 23

How is the complement system controlled?

Answer 23

short life of components
dilution inf fluids
specific regulatory proteins that are circulating or membrane bound

Question 24

What is the function of the complement system?

Answer 24

opsonisation, lysis, activation of inflammatory response, clearance of immune complexes

Question 25

Give the characteristics of a system ‘acute-phase’ response

Answer 25

1-2 days after local inflammatory response
fever
increased WBC production
acute phase protein production in liver
cytokine induced

Question 26

Name proteins involved in the acute phase

Answer 26

C-reactive protein, mannan binding lectin, complement, fibrinogen