Immune response to infection

Question 1

What part of the immune system do natural killer cells belong to?

Answer 1

Innate immune system.

Question 2

What are the 4 pathogen niches?

Answer 2

Extracellular(staphylococcus, streptococcus), intracellular but vacuolar(salmonella and chlamydia), surface adherent(E coli) and intracellular but cytosolic (viruses).

Question 3

What are the first cells to respond to infection?

Answer 3

Neutrophils followed by macrophages.

Question 4

If macrophages aren’t controlled what can happen?

Answer 4

Formation of granulomas.

Question 5

What is the macrophage t cell interaction that leads to macrophage activation?

Answer 5

Macrophages releases IL-12. T helper cell responds by releasing IF gamma and this activates macrophage. Macrophage phagocytoses pathogen.

Question 6

What does IL-12 do to a T cell?

Answer 6

Promotes T cell replication.

Question 7

What does Interferon gamma released from T cells do?

Answer 7

Upregulates MHC II expression.

Question 8

What pathogens do macrophages target?

Answer 8

Intracellular pathogens.

Question 9

What cells predominantly produces type 1 interferons such as IF-alpha and IF-beta?

Answer 9

Virally infected cells.

Question 10

What do interferons do?

Answer 10

Promote transcription of anti viral genes. Enhances t cell response by higher MHC expression and tissue repair.

Question 11

What do anti viral genes promoted by interferons code for?

Answer 11

Nucleases, viral entry/exit inhibitors, viral uncoating inhibitors, protein translation inhibitors.

Question 12

What interferon is produced for viruses?

Answer 12

Alpha and beta.

Question 13

What interferon is produced for bacteria?

Answer 13

Gamma.

Question 14

Virus-infected cells are killed by what immune cells?

Answer 14

Cytotoxic T lymphocytes (CTLs) or Natural Killer (NK) cells.

Question 15

How does killing of cells prevent spread of pathogens?

Answer 15

Viral replication need cells to replicate. Kills viruses inside. Apoptosis is controlled inflammation.

Question 16

What can triggers expression of genes that activate cellular effector mechanisms that kill intracellular pathogen?

Answer 16

Binding of complement protein or cytokine to cell surface.

Question 17

What are the two cellular effector mechanisms that can kill intracellular pathogens?

Answer 17

Reactive Oxygen and Nitric oxide. Acidification and digestion within phagosomes.

Question 18

What soluble molecules can inhibit microbes?

Answer 18

Complement mediated bacterial destruction. Lectin binding to neutralise cell attachment or entry.

Question 19

What cell does Th1 primarily activate

Answer 19

Macrophages by interferon gamma.

Question 20

What cell does Th2 primarily activate?

Answer 20

Eosinophils.

Question 21

What cell does Th17 primarily activate?

Answer 21

Neutrophils.

Question 22

What activates innate immune cells?

Answer 22

Detection of microbial ligands (PAMPS). Gene expression changes driven by specific combination of cytokines

Question 23

What happens to lymphocytes after they recognise antigen and become activated?

Answer 23

Proliferation and differentiation e.g into different t helper cell classes.

Question 24

What immune cells would you expect to see 3-5 days after infection?

Answer 24

Plasma cells and effector T cells.

Question 25

T lymphocyte count as we age?

Answer 25

Naive T cell count decreases due to thymic involution but memory T cell count increases.

Question 26

In a protozoa infection what T cell would be produced?

Answer 26

Th1 cells.

Question 27

In a fungi infection what T cell would be produced?

Answer 27

Th17 cells.

Question 28

In a viral infection what T cell would be produced?

Answer 28

Cytotoxic T lymphocytes.

Question 29

In a helminth infection what T cell would be produced?

Answer 29

Th2 cells.

Question 30

What immune cell count can be reduced if you get infected by HIV?

Answer 30

Reduced CD4 T helper cells.

Question 31

In X-linked agammaglobulinaemia what would be reduced in the blood?

Answer 31

Decreased serum IgG of all types.

Question 32

In Severe combined immunodeficiency (SCID) what would be reduced in the blood?

Answer 32

Low lymphocyte count.

Question 33

What occurs in chronic granulomatous disease?

Answer 33

Loss of reactive oxygen species production and so neutrophils, monocytes, and macrophages can’t destroy certain microbes.

Question 34

What occurs in Chédiak-Higashi syndrome?

Answer 34

Compromised lysosomes.