Cytokines

Question 1

What are cytokines?

Answer 1

small secreted proteins that perform cell-to-cell communication in their local area (nearby cells) at low concentrations, effects are short lived bc/ they get broken down

Question 2

What are interferons?

Answer 2

IFNs = small cytokines interfering with viral function

Question 3

What are interleukins?

Answer 3

ILs = communication between leukocytes

Question 4

What do chemokines aid in?

Answer 4

cell movement = chemotaxis

Question 5

What are growth factors?

Answer 5

cytokines (small proteins) that aid in the proliferation & differentiation of cells

Question 6

What are cytotoxins?

Answer 6

apoptosis of cells,

eg tumor necrosis factor (TNF)

Question 7

What is the complement system?

Answer 7

around 30 proteins & glycoproteins in the serum at high conc., complement the activity of specific antibody in lysing bacteria which is triggered by few bacteria starting an enzyme cascade system that can make a small response into a rapid, highly amplified response

Question 8

Where are the glycoproteins & proteins of the complement system produced predominantly?

Answer 8

liver

Question 9

How do you activate the inactive enzymatic precursors of complements?

Answer 9

one initial cleavage

Question 10

What are the three ways the complement pathway is activated?

Answer 10

Classical pathway = when an antibody binds to an antigen, antibody changes conformation
alternative pathway = directly by the surfaces of pathogens
lectin pathway = classical pathway w/o antibodies, proteins eg. C reactive protein bind to pathogens and activate complements

Question 11

Which protein is attacked by all three pathways to activate it and it triggers the final common pathway?

Answer 11

C3b

Question 12

What happens after the final common pathway in complement activation?

Answer 12

Membrane Attack Complex formed-> lysis of the pathogen (forms holes in it)

Question 13

How is the complement pathway controlled to prevent host cell lysis?

Answer 13

• complements are labile= short half life, turned over by the body quickly
• complements diluted in body fluids, don’t stay in circulation but also in tissues (eg. muscles)
• regulatory membrane bound & circulating proteins that inhibit the complements

Question 14

What is the acute-phase response?

Answer 14

immune response that happens 1-2 days later after infection w/ inflammation

• increased WBC production (leukocytosis)
• fever
• cytokines released -> to signal the production of acute-phase proteins by liver (endocrine manner signalling)

Question 15

What are acute-phase proteins?

Answer 15

complement activating proteins through the lectin pathway:
eg. mannan binding lectin (MBL)
& C-reactive protein

-fibrinogen = factor 1 (clotting factor)

Question 16

Why is C-reactive protein used diagnostically as a marker for inflammation?

Answer 16

• level may increase 1000x following infection

marker of inflammation eg. auto-immune diseases