Cytokines

Question 1

what are cytokines? function?

Answer 1

small secreted proteins that regulate the amplitude and duration of immune and inflammatory responses

Question 2

what type of receptors do cytokines bind to? what happens upon cytokine binding to a receptor?

Answer 2

normally to dimeric receptors -> the binding brings the two parts of the receptor together which induces a signalling cascade. leads to the upregulation of gene transcription -> ultimately to activate the cell specific function

Question 3

name different cytokines (6)

Answer 3

interleukins, interferons, tumour necrosis factors, growth factors, colony stimulating factors, chemokines

Question 4

which cytokines does the haematopoietic family include?

Answer 4

interleukins and colony stimulating factors

Question 5

3 types of haematopoietic family cytokine receptors (and an example of cytokine they bind)

Answer 5

1. alpha-beta receptor ->IL-13, erythropoietin, and growth hormone
   2.receptors containing a common beta chain -> IL-13, IL-5
2. receptors containing common gamma chain -> IL-2, IL-4

Question 6

structure of the IL-2 receptor:

Answer 6

contains a common gamma chain + a unique IL-2 beta chain. in this form it is classed as a low affinity receptor. once IL-2 binds low affinity IL-2 receptor -> it upregulates the expression of an alpha chain (also called CD25) = IL-2 high affinity receptor

Question 7

functions of IL-2

Answer 7

autocrine function (the upregulation of CD25), NK cell activation, monocyte activation, activation and promotion of cell division -> B and T cells, and also mediator release -> e.g. IFN-gamma

Question 8

cytokine families (4)

Answer 8

haematopoietic, TNF, INF cytokine fam, and chemokines

Question 9

the strucute of TNF

Answer 9

trimeric form -> 3 TNF protein together bind its (trimeric) receptor

Question 10

what cytokine family does IL-10 belong to?

Answer 10

interferon cytokine family

Question 11

what is the main function of interferons?

Answer 11

interfere with viral replication -> virall-infected cells produce interferons to help the immune system clear out the infection

Question 12

what is the main function (mechanism of action) of IFN-gamma?

Answer 12

upergulation of MHC molecules

Question 13

which cells are heavily influenced by IFN-gamma and why?

Answer 13

NK cells because they normally kill cells which do not express MHC class I molecules (mechanism of some viruses) –> IFN-gamma acts as an additional signal

Question 14

how are chemokines divided and what are the different types?

Answer 14

depending on their structure.
1. CXCL chemokines -> cysteine / amino acid / cysteine
2. CC chemokines -> cysteine next to cysteine

Question 15

an example of a CXCL chemokine

Answer 15

CXCL (or IL-8)
->produced by monocytes, macrophages, keratinocytes and endothelial cells
-> very important in attracting neutrophils from the blood circulation into tissues (during an infection)

Question 16

an example of a CXCL chemokine + which cells secrete it + function

Answer 16

CXCL (or IL-8)
->produced by monocytes, macrophages, keratinocytes and endothelial cells
-> very important in attracting neutrophils from the blood circulation into tissues (during an infection)

Question 17

an example of a CC chemokine + which cells secrete it and function

Answer 17

CCL5 (or RANTES)
-> produced by T cells, endothelial cells, and platelets
-> recruits monocytes, NK and T cells, eosinophils and DCs
major effects: degranulation of basophils, activation of T cells, chronic inflammation

Question 18

what cytokines are secreted by an activated macrophage?

Answer 18

IL-1beta, TNF-alpha, IL-6, CXCL8, IL-12

Question 19

IL-1beta function

Answer 19

activates vascular endothelium, activates lymphocytes, local tissue destruction

Question 20

IL-6

Answer 20

lymphocyte activation, increased antibody production

Question 21

IL-12

Answer 21

activates NK cells, induces the differentiation of CD4 T cells into Th1 cells

Question 22

what is the function of cytokines secreted by DCs?

Answer 22

the cytokines produced by DCs influence T cell responses –> T cell activation signal 3 (determines the polarization of the helper T cell)

Question 23

the major categories of ILC (4) and their function

Answer 23

NK cells -> immunity against viruses and intracellular pathogens
ILC1 -> (same as NK cells)
ILC2 ->immuity against multicellular parasites
ILC3 -> immunity against extracellular bacteria and fungi