Communication Between Immune Cells

Question 1

Cytokines function

Answer 1

Mediate communication between cells of the immune system
Bind to specific receptors on target cells
Generally soluble

Question 2

How do cytokines work?

Answer 2

Inducing stimulus causes cytokine-producing cell to produce cytokines
Cytokines bind to receptor on target cell
Gene activation
Leads to desired biological effects

Question 3

What is autocrine action of cytokines?

Answer 3

Cytokines produced and bind to receptor on same cell

Question 4

What is paracrine action of cytokines?

Answer 4

Cytokines produced and bind to receptor on nearby cell

Question 5

What is endocrine action of cytokines?

Answer 5

Cytokines produced
Enter circulation
Bind to receptor on distant cell

Question 6

Define pleitropy (cytokines)

Answer 6

One cytokines has several different functions

Question 7

Define redundancy (cytokines)

Answer 7

Several cytokines can perform same function

Question 8

Define synergy (cytokines)

Answer 8

Cytokines work together

Question 9

Define antagonism (cytokines)

Answer 9

Cytokines inhibit action of other cytokines

Question 10

Which cells produce the majority of cytokines?

Answer 10

T helper cells
Dendritic cells
Macrophages

Question 11

Describe T cells

Answer 11

Part of adaptive immune response
Mature in thymus and migrate to secondary lymphoid tissue
Express T cell receptors which recognise processed antigens present on surface of APCs (macrophages, dendritic cells, B cells)
Differentiate into CD4+ TH cells or CD8+ cytotoxic T lymphocytes

Question 12

TH1 cell function

Answer 12

Recognises complex of peptide antigen with MHC class 2 and activates macrophage

Question 13

TH2 cell function

Answer 13

Recognises complex of peptide antigen with MHC class 2 and activates B cell

Question 14

What drives T helper cell differentiation?

Answer 14

Cytokines

Question 15

List 5 types of cytokines

Answer 15

Interleukins (IL)
Tumour necrosis factors (TNF)
Interferons (IFN)
Colony stimulating factors (CSF)
Chemokines

Question 16

Where do interleukins act?

Answer 16

Between leukocytes

Question 17

IL-1alpha, IL-1beta and IL-6 function

Answer 17

Pro-inflammatory (also TNF alpha)

Question 18

IL-10 and IL-4 function

Answer 18

Anti-inflammatory (also TGF beta)

Question 19

IL-2 function

Answer 19

T cell proliferation and differentiation

Question 20

IL-4 function

Answer 20

B cell activation and differentiation into antibody-secreting plasma cells (Ig class switching)

Question 21

IL-5 function

Answer 21

Activation of eosinophils

Question 22

Describe type 1interferons and how they work

Answer 22

First line of defence in viral infections
Interferon alpha and beta
Up-regulation of MHC class 1 presentation
Activation of cytotoxic CD8 response
Destruction of viral RNA
Inhibition of protein synthesis

Question 23

Describe type 2 interferons and how they work

Answer 23

Interferon gamma
Key cytokines in TH1 immune response
Activation of macrophages
Up-regulation of MHC expression
Clearance of intracellular pathogens

Question 24

How do colony-stimulating factors work and name 3 subtypes

Answer 24

Mediate growth and differentiation of immature leukocytes in the bone marrow

M-CSF = macrophage CSF
G-CSF = granulocyte CSF
GM-CSF = macrophage/granulocyte CSF

Question 25

Define chemotaxis

Answer 25

Cell movement directed by soluble factors

Question 26

What are chemokines and what do they do?

Answer 26

Small cytokines Induce movement of leukocytes along concentration gradient

Question 27

Effect of cytokine storm on body

Answer 27

Dilation of blood vessels Leakage of fluid into body tissues Perturbation of blood supply Tissue injury Widespread blood clotting Organ failure

Question 28

Symptoms of cytokines storm

Answer 28

Fever Circulatory collapse DIC haemorrhaging necrosis Multiple organ failure

Question 29

How is type 2 diabetes related to cytokines?

Answer 29

Expression of TNF alpha by adipose tissue of obese individuals Decreased cellular response to insulin and glucose uptake

Question 30

How is cancer related to cytokines?

Answer 30

IL-6 over-expression in most types of tumours Enhanced proliferation, angiogenesis, invasive need and metastasis Increased metabolism —> cachexia

Question 31

Risks of medications that reduce cytokines activity

Answer 31

Increased risk of infection and malignancy

Question 32

Risk of very short half life of cytokines in medications

Answer 32

Frequent administration

Question 33

Risk of pleiotropic action of cytokines in medications

Answer 33

Unpredictable and severe side effects