The immune system and disease 1

Question 1

Function of macrophages

Answer 1

Sentinels under skin/gut/resp mucosa. Process cellular debris. Act as APC if primed , activate T cells and can directly kill pathogens also.

Question 2

MHC expression in macrophages

Answer 2

MHC II- low levels in normally upregulated when activated

Question 3

How are macrophages activated?

Answer 3

When barriers are penetrated, NK and T cells release IFNg which activates T cell

Question 4

How does macrophage recognise pathogens?

Answer 4

PRR (eg Toll like) on macrophage recognise PAMPs- non-specific

Question 5

How does a macrophage become a more effective killer when hyperactivated?

Answer 5

Increases reactive oxygen molecules and number of lysosomes

Question 6

Cytokines secreted by activated macrophage

Answer 6

IL-1B, TNF-a, IL-4, CXCL-8, IL-12

Question 7

Macrophage response to activation (receptors)

Answer 7

Upregulate MHC and costim molecules (CD80 CD86) and increase capillary endothelial cell adhesion molecule expression (allow extravasation)

Question 8

Macrophage response to activation (pathway activation and cytokines)

Answer 8

Activates complement cascade
TNF-a secretion (activates vasc endothelium, increase vasc permeability allowing more complement, Ig, cells and fluid to the site)

Question 9

NK cells origin

Answer 9

Bone marrow

Question 10

NK cells receptors- specific or non-specific?

Answer 10

Non-specific

Question 11

NK cell function

Answer 11

Kill tumour and virally infected cells

Also secrete IFN-g to activate macrophages

Question 12

How are NK cells further activated?

Answer 12

Macrophages secrete TNF-a and IL12 which further activates NK cells

Question 13

Neutrophils origin and life span

Answer 13

Bone marrow derived, 5 day life span

Question 14

Neutrophil function

Answer 14

Ingest and kill microbes - not APC

Question 15

How are neutrophils attracted to infection site?

Answer 15

TNF-a

Question 16

Dendritic cell origin

Answer 16

Bone marrow derived

Question 17

Resting dendritic cell function and features

Answer 17

Sentinel beneath epithelial barriers, sampling the environment and with low levels of B& (costim) and MHC I&II - bridges innate and adaptive immunity

Question 18

How are dendritic cells activated and what happens?

Answer 18

They are activated by IFNg or TLR stimulation, upregulate B7 and MHC I&II, phagocytose pathogen and then travel to lymph node.

Question 19

What do activated dendritic cells do at the lymph node?

Answer 19

Sampled by T-cells and activate one with the right receptor

Secrete chemokine to attract monocytes to infection and continue sampling the site

Question 20

How long does the dendritic cell survive at lymph node and what is the significance of this?

Answer 20

7 days - if pathogen still present at site of infection, need new dendritic cell to come to the lymph node and activate T cells