principles of immune response

Question 1

define cytokines

Answer 1

any small soluble protein mediator secreted by certain cells of the immune system that have an effect on other cells

Question 2

in macrophages, what initiates a response release of cytokines

Answer 2

bacteria binding to macrophage receptor

Question 3

what cells secrete cytokines in innate immunity

Answer 3

macrophages, mast cells, natural killer cells

Question 4

what cells secrete cytokines in adaptive immunity

Answer 4

T and B lymphocytes, dendritic cells

Question 5

what complement proteins activate mast cells

Answer 5

anaphylatoxins

Question 6

what cytokine do natural killer cells secrete

Answer 6

interferon-y

Question 7

3 features of mode of action of cytokines

Answer 7

generally act locally, biological effects at very low concentrations, short-lived

Question 8

5 types of cytokines

Answer 8

interleukins, interferons, chemokines, growth factors, cytotoxic

Question 9

what cells do interleukins communicate between

Answer 9

leukocytes

Question 10

what effect do type 1 interferons have

Answer 10

anti-viral

Question 11

what are chemokines involved in

Answer 11

chemotaxis

Question 12

what 2 effects do growth factors have

Answer 12

proliferation, differentiation

Question 13

what do cytotoxic cytokines induce

Answer 13

cell death, e.g. tumour necrosis factor (TNF)

Question 14

cytokine mode of action

Answer 14

work by binding to specific receptors on target cells, causing specific gene activation; one cell produces a cocktail of cytokines; diagram

Question 15

what is the major role of the complement system

Answer 15

complementing activity of specific antibody in lysing bacteria

Question 16

how is the major role of the complement system performed

Answer 16

a protein cascade occurs where holes are rapidly punched in the microbial outer membrane, coated for phagocytosis (opsonisation) and the production of chemoattractants for cell recruitment

Question 17

what is opsonisation

Answer 17

coating of microorganisms with proteins (opsonins) to facilitate phagocytosis; opsonins bind to antigen and phagocytes

Question 18

how many (glyco)proteins are involved in the complement system

Answer 18

30 in serum and tissue

Question 19

what forms the activated proteins

Answer 19

triggered enzyme cascade system

Question 20

describe the triggered enzyme cascade system

Answer 20

inactive enzymes present as precursors in liver (humoral) → initial event rapidly amplified → parts of enzyme cleaved → rapidly amplified

Question 21

4 functions of complement system

Answer 21

lysis (not phagocytosis), opsonisation, activation of inflammatory response, clearance of immune complexes

Question 22

what are the 2 types of opsonin

Answer 22

antibodies, complement proteins

Question 23

3 complement activation pathways

Answer 23

classical, lectin, alternative

Question 24

describe classical complement activation pathway

Answer 24

antigen and antibody interaction (pro-inflammatory molecules)

Question 25

describe lectin complement activation pathway

Answer 25

proteins bind to carbohydrates (MBL, CRP) on bacteria, triggering activation

Question 26

describe alternative complement activation pathway

Answer 26

bacterial surfaces undergo direct adhesion by complement proteins

Question 27

what do all 3 complement activation pathways activate

Answer 27

C3b, which is the main opsonin

Question 28

what is the final common pathway from C3b in complement activation pathways, and what is the outcome

Answer 28

membrane attack complec (MAC), causing cell lysis

Question 29

3 features of complement proteins which allow control

Answer 29

short half-life, can be diluted in biological fluids, specific regulatory proteins in circulation or membrane-bound

Question 30

what is the systemic “actute-phase” response

Answer 30

fever, increased leukocyte production and production of “acute-phase” proteins in liver 1-2 days after local inflammatory response

Question 31

what is required to induce systemic “actute-phase” response

Answer 31

cytokine production

Question 32

what are the 3 soluble mediators in innate immunity

Answer 32

acute-phase proteins, cytokines, complement proteins

Question 33

what are the 2 soluble mediators in adaptive immunity

Answer 33

cytokines, antibodies