7- Cytokines and Receptors

Question 1

What are the properties of cytokines?

Answer 1

• low molecular weight, secreted ‘messenger’ proteins
• regulate intensity and duration of innate and adaptive immunity responses
• activity is receptor-mediated

Question 2

What are the three types of activity cytokines can produce?

Answer 2

• Autocrine: act on the cell that produced it
• Paracrine: act on another cell nerarby
• Endocrine: act at a distant location from where it is produced

Question 3

Define monokines

Answer 3

proteins from monocytes

Question 4

Define lymphokines

Answer 4

proteins from lymphocytes

Question 5

Define interleukin

Answer 5

between lymphocytes

Question 6

Define interferons

Answer 6

interfere with viral replication

Question 7

Define chemokines

Answer 7

chemotactic cytokines that attract specific cells to their locations

Question 8

Define colony stimulating factors (CSF)

Answer 8

stimulate colony formation in mone marrow, stimulate stem cell differentiation

Question 9

Define growth factor

Answer 9

stimulate cells to grow in vitro

Question 10

Describe the pathways that trigger cytokine release

Answer 10

1) Antigens bind to TCRs and release IFN-gamma and IL-2 or IL-4, IL-10, IL-13

2) PAMPs bind to TLR (type of PRR) and release IL-1, TNF-alpha, IL-6

3) Antibodies bind to FcR (Fc portion of antibodies) and release IL-1 and TNF-alpha

Question 11

Describe the importance of cytokines that mediate and regulate innate immunity

Answer 11

• Particularly important in the first few days of an infection when the adaptive immunity response has not yet started
• act immediately and some influence the adaptive immune response that develops
• examples: IL-1 and TNF-alpha (proinflammatory), IL-12, type-1 interferons

Question 12

What are the roles of IL-12?

Answer 12

• produced by APCs in response to bacteria and viruses
• activate NK cells to be more efficient killers
• introduce IFN-gamma production
• stimulate differentiation of TH1 cells

Question 13

What are the type 1 interferons and what is their role?

Answer 13

• IFN-alpha and IFN-beta
• part of innate immunity
• produced by virally infected nucleated cells
• make other cells resistant to viral infection

Question 14

What are the type 2 interferons and what is their role?

Answer 14

Interferon gamma (IFN-gamma)
- role in innate and adaptive immunity
- produced by NK cells and activated TH1
- Antiviral
- activates macrophages, neutrophils, and NK cells
- Promotes TH1 development
- Inhibits TH2 development
- Promotes B cell to produce IgG
- upregulates MHC expression on APCs

Question 15

Cytokines that mediate and regulate adaptive immunity are produced by?

Answer 15

T lymphocytes

Question 16

List and describe the cytokines that regulate lymphocyte activation, growth and differentiation in adaptive immunity

Answer 16

• IL-2: lymphocyte proliferation
• IL-4: stimulate TH2, B cell differentiation (IgE)
• IL-13: B cell differentiation (IgE)
• IL-10: Inhibit TH1
• TGF-beta: Treg cytokine, B cell differentiation (IgA)
• IFN-gamma: B cell differentiation (IgG)

Question 17

List and describe the cytokines that enhance innate immunity through adaptive immunity

Answer 17

• IFN-gamma: activate macrophages
• TNF: activate endothelial cells and neutrophils
• IL-5: eosinophil activation and generation

Question 18

List the major cytokines that stimulate hematopoiesis

Answer 18

• erythropoietin
• thrombopoietin
• IL-3
• IL-5
• GM-CSF
• G-CSF
• M-CSF