Immune Response to Infection

Question 1

Different pathogen niches

Answer 1

Extra cell
Intracellular
Surface adherent
Intracellular but cystolic

Question 2

Extra cellular

Answer 2

e.g. Staphylococcus, Streptococcus, Candida, microbiota, worms)

Question 3

Intracellular

Answer 3

e.g. Salmonella, Chlamydia, Legionella, Coxiella, Plasmodium, helminths)

Question 4

Surface adherents

Answer 4

(e.g. enteropathogenic & enterohaemorrhagic E. coli)

Question 5

Intracellular but cystolic

Answer 5

(e.g. viruses, Listeria, Burkholderia, Mycobacterium)

Question 6

Humoral aspects of innate immunity

Answer 6

Humoral:

Complement, Lectins (collectins, ficolins), Pentraxins, Antimicrobial peptides

Question 7

How does an immune response to infection start

Answer 7

Tissue damage ( e.g.injury)
Molecular detection of microbes
Intra cellular communication ( interleukins )
Priming the adaptive immune response

Question 8

How does an immune response to infection end

Answer 8

Clearing infection
Stopping inflammatory cytokines production
Repairing tissue damage
Immune memory

Question 9

What differences in molecules are there between the innate and the adaptive immune system

Answer 9

Timing of the response
	Cell types 
	Receptors & ligands
	Cytokines & chemokines
	Molecular effector machineries

Question 10

Uncontrolled activities of phagocytes lead to

Answer 10

Granulomas
Excessive inflammation & inappropriate adaptive immunity
Tissue damage

Question 11

What helps convert a resting cell to a specialised cell

Answer 11

Gene expression means that the cell is able to better respond to pathogens

Question 12

Are cytokine responses to pathogens unique

Answer 12

Yes

Question 13

Phagocyte response to bacteria

Answer 13

Immune response when bacterial mRNA is release
• Inflammatory cytokines 
• Antimicrobial genes
• Metabolic genes
• Immunomodulatory genes

No immune response if dead pathogen ingested and so no mRNA released
Resolution of inflammation

Question 14

Phagocyte response to fungi

Answer 14

• Proinflammatory cytokines
• Antimicrobial genes
• Metabolic genes
• Immunomodulatory genes

Question 15

Phagocyte response to viruses

Answer 15

• Interferon production
• Proinflammatory cytokines
• Antiviral genes
• Immunomodulatory genes

Question 16

Phagocyte activation and pathogen killing, which interferon is imp?

Answer 16

Interferon gamme (IFN-gamma) is important 
	Induced by microbes & cytokines

Humans lacking IFN gamma or have mutations in these pathways are susceptible to salmenolois and micro bacterial infections

Question 17

Activated macrophages display enhanced…

Answer 17

Phagocytosis & Migration
Cytokine/chemokine production
Expression of cell surface molecules
Antimicrobial activity
Antigen presentation & T cell activation
“Alternatively” activated macrophages are anti-inflammatory

Question 18

IFN gamma

Answer 18

Extra cellular bacterial pathogens

Question 19

IFN alpha/beta

Answer 19

Anti viral

Question 20

Antiviral genes include

Answer 20

Nucleases
Inhibitors of virus entry & exit
Inhibitors of viral uncoating and replication
Inhibitors of protein translation

Question 21

Immunomodulatiry roles of interferons

Answer 21

Enhanced T-cell responses
Anti-inflammatory actions
Tissue repair

Question 22

Every single primary infected cells can produce type 1 interferon

Answer 22

True

Question 23

Where are types 1-3 interferons produced

Answer 23

Type 3; epithelial cell surfaces
Type 1; produced deeper down
Type 2; only produced in lymphocytes

Question 24

NK cells

Answer 24

Virus-infected cells are killed by the actions of cytotoxic T lymphocytes (CTLs) or Natural Killer (NK) cells

Cell death removes viral replicative niches

CTLs and NK cells directly kill infected cells (contact-dependent)

Host cells infected with intracellular bacterial pathogens also undergo forms of cell death (contact-independent) - some cytokines can also induce cell death (cytokine-mediated)

So virus can no longer replicate

Question 25

Type two interferon promotes....

Answer 25

Anti bacterial immunity

Question 26

Types 1 and 3 interferons promote

Answer 26

Antiviral responses

Question 27

Soluble effector mechanisms

Answer 27

``` Complement mediated bacterial destruction Lectin-binding to neutralise cell attachment or entry Iron chelation (siderophores) to prevent replication Antibiotic-like peptides ```

Question 28

Cellular effector mechanisms of immunity

Answer 28

Reactive Oxygen and Nitrogen radicals | Acidification and digestion within phagosomes

Question 29

How do Dcs and macrophages activate T cells

Answer 29

Dendritic cells and macrophages present antigens in combination with MHC-I or MHC-II to T cells. Cytokines produced by antigen-presenting cells produce a suitable milieu for T-cell activation E.g. IL-12 promotes T-cell replication These are specific to the type of pathogen! T cells provide cytokines that activate phagocytes E.g. IFNg upregulates MHC-II expression for antigen presentation Responses are specific to general class of pathogens

Question 30

Broad classification of T cell function

Answer 30

Phagocyte activation Enhanced killing of pathogens Inflammation Direct killing of infected cells Removal of replicative niches B cell activation Antibody production & affinity maturation Innate lymphoid cells/gd T cells A type of early responders (MHC independent actions)

Question 31

CD4 T cellsz usually in

Answer 31

Bacteria. Cells

Question 32

CD8 cells usually in

Answer 32

Viral infections

Question 33

Look at ‘Microbe-specific phagocyte responses induce the appropriate lymphocyte phase’ table in notes

Answer 33

Look at ‘Microbe-specific phagocyte responses induce the appropriate lymphocyte phase’ table in notes

Question 34

Impact of age on immune cell response

Answer 34

Memory T cells have encountered many diff infections over the period of years. Increased age, decreased immunity

Question 35

Defect in leukocyte adhesion

Answer 35

Genes involved in migration and adhesion

Question 36

Chrniicngranulotamous disease

Answer 36

Loss of reactive o2 species

Question 37

Chédiak-Higashi syndrome

Answer 37

Compromised lysosomes

Question 38

(SCID)

Answer 38

Reduction in number and function of T cells and B cells

Question 39

X-linked agammaglobulinaemia

Answer 39

Decreased serum IgG of all types

Question 40

HIV

Answer 40

Reduced CD4 T helper cells

Question 41

Irradiation and chemotherapy ( cancer treatment)

Answer 41

Loss of bone marrow precursor

Question 42

Immunosupression ( graft rejection / chronic disease)

Answer 42

Depletion or impairment of lymphocytes