Lecture 4- Immune mechanisms: innate cellular immunity

Question 1

2 types of progenitor cell and roughly what they make

Answer 1

myeloid progenitor cell- makes innate cells
lymphoid progenitor cells- makes adaptive/NK cells

Question 2

stromal cell immunity- example

Answer 2

epithelial cells expressing PRRs
enterocytes- mucus secretion which can change according to MUC expression, goblet cells which have antimicrobial function
enterocytes also have PRRs and are involved in early response to infection

Question 3

macrophage and monocyte function

Answer 3

recognition of early pathogen invasion (lots of PRRs), recruitment of other cells
also involved in phagocytosis, can be alternatively activated to aid healing

Question 4

how can macrophages be induced and what is the immediate step

Answer 4

PRR signals, leading to secretion of pro-inflammatory cytokines

Question 5

example of macrophage action towards the end of an infection

Answer 5

IL-4 triggering wound-healing macrophages to differentiate (more balanced IL-10 and 12)

Question 5

some examples of macrophage and monocyte types

Answer 5

inflammatory and resident monocytes
alveolar macrophages in the lungs, osteoclast in the bone

Question 6

collective name for polymorphonuclear cells, and the main types

Answer 6

granulocytes
neutrophils, esoinophils, basophils

Question 7

neutrophil function

Answer 7

phagocytosis mostly- rapid recruitment, phagocytosis, and death
also have a lot of antimicrobials

Question 8

effector mechanism of neutrophils

Answer 8

-can release granules containing antimicrobials
-NETs- neutrophil extracellular traps- DNA coated with antimicrobial molecules, assembled outside of the cell- often form following cell death (known as NETosis)

Question 9

problems caused by NETs

Answer 9

interfering with other cell types, clogging blood vessels, acting as tumour scaffolding

Question 10

esoinophil functions

Answer 10

degranulation at the surface of large pathogens such as helminths
general production of cytotoxic molecules (ROSs, proteases) and signalling molecules, such as cytokines and growth factors

Question 11

basophil function

Answer 11

similar to esoinophils, especially high producers of IL4

Question 12

cells involved in allergies

Answer 12

esoinophils, basophils

Question 13

example of cells which can phagocytose

Answer 13

macrophages, neutrophils, dendritic cells

Question 14

3 ways cellular material can be taken up

Answer 14

receptor-mediated endocytosis, helps differentiate what is taken up due to the receptor
pinocytosis (small things)- involves small vesicles and is non-specific
phagocytosis- larger things, involves specialised cells

Question 15

dendritic cell function

Answer 15

‘professional APC’- express a lot of MHC to aid T cell communication

Question 16

special features of dendritic cells

Answer 16

present MHCII- only done by professional APCs
only cells to interact with naive t cells

Question 17

how do DCs get to the lymph nodes

Answer 17

after PRRs are triggered, they move towards the lymph nodes and interact with T cells there

Question 18

3 signal model of T cell activation

Answer 18

TCR and MHC interaction
co-stimulation
cytokines

Question 19

problem with activating CD8 cells and how it is overcome

Answer 19

CD8 cells recognise MHC1
can be solved with cross-presentation, dendrite moving antigens to an endogenous pathway rather than the exogenous pathway used to activate CD4s

Question 20

what are natural killer cells

Answer 20

innate lymphocytes which don’t express TCRs or CD3
do what they say- check if cells are normal, kill ones which aren’t e.g. tumours or virus-infected cells

Question 21

how are NKs activated

Answer 21

looking for the correct amount of MHC class I on a cell surface- viruses limit this expression, so acts as a detection mechanism for virus-infected cells

Question 22

how can the sensitivity of NKs change

Answer 22

‘on’ and ‘off’ signals- more cytokines for example can increase activation and make these cells kill more

Question 23

NK mechanism of action

Answer 23

performin and granzymes to help kill, IFNgamma which can enhance the cytotoxic response