C2 soluble mediators

Question 1

2 soluble blood components

Answer 1

complement
antimicrobial proteins

Question 2

types of antimicrobial proteins and their role (are the inactive or active)

Answer 2

lactoferrin- binds iron
bactericidal/permeability- increasing protein
a and b defensins- cationic peptides, disrupt membranes
often present in inactive form and activated when an immune responses is taking place

Question 3

what are the three pathways that activate complement and what is needed

Answer 3

classical
alternative
lectin
lots of proteases (an enzyme that catalyses proteolysis, breaks down proteins into smaller polypeptides/single aa, act in a controlled manner)

Question 4

what is the exception to the a-small product rule

Answer 4

C2 where C2a is big

Question 5

what do anaphylatoxins initiate with receptor example

Answer 5

may initiate localised inflammatory responses by binding to specific receptors such as
complement component 3a receptor 1 and complement component 5a receptor 1

Question 6

what do the b in complement pathways result in and bind to

Answer 6

Big product
bind to targets near activation sites
opsonins ie C3b, C3dg, and iC3b interact with cell surface receptors such as complement component receptor 1
complement component receptor 2
integrins alpha-M/beta-2 integrin
alpha-X/beta-2 integrin

Question 7

function of active form C1q

Answer 7

binds directly to pathogen surfaces or indirectly to antibody bound to pathogens thus allowing autoactivation of C1r

Question 8

function of active form C1r

Answer 8

cleaves C1s to activate protease

Question 9

function of active form C1s

Answer 9

cleaves C4 and C2

Question 10

function of active form C4b

Answer 10

covalently binds to pathogen and opsonises it
binds C2 for cleavage by C1s

Question 11

function of active form C4a

Answer 11

peptide mediator of inflammation (weak acctivity)

Question 12

function of active form C2a

Answer 12

active enzyme of classical pathway C3/C5 convertase
cleaves C3 and C5

Question 13

function of active form C2b

Answer 13

precursor of vasoactive C2 kinin

Question 14

function of active form C3b

Answer 14

binds to pathogen surface and acts as opsonin
initiates amplification via the alternative pathway
binds C5 for cleavage by C2a

Question 15

function of active form C3a

Answer 15

peptide mediator of inflammation (intermediate activity)

Question 16

what is the classical pathway initiated by

Answer 16

by C1 components

Question 17

what is the alternative pathway initiated by

Answer 17

by C3

Question 18

what is the lectin pathway initiated by

Answer 18

by mannan binding protein (mannan binding ligand MBL)

Question 19

end point of the lectin pathway

Answer 19

C3a and C5a recruit phagocytic cells to the site of infection and promote inflammation

Question 20

end point of classical pathway

Answer 20

phagocytes with receptors for C3b engulf and destroy pathogen

Question 21

end point of alternative pathway

Answer 21

completion of the complement cascade leads to formation of a membrane attack complex (MAC) which disrupts cell membrane and causes lysis

Question 22

defensins, cathelicidins, and histatins and activated by what to release what

Answer 22

activated by proteolysis to release an amphipathic antimicrobial peptide
(amphipathic- peptide with both hydrophilic and hydrophobic parts

Question 23

how do lysozymes act on bacteria

Answer 23

bacteria have an outer membrane that has carbohydrate chains, interlocked by short peptide strands
lysozymes break down carb chain and damages structural integrity of the bactrial outer membrane
bacteria burst under their own internal pressure

Question 24

what are lysozymes inactive and active against

Answer 24

inactive against most gram -ve bacteria
cannot penetrate the outer membrane to reach peptidoglycan
very active against gram +ve bacteria

Question 25

how do defensins work

Answer 25

disrupt membrane of pathogen forming a pore
electrostatic attraction and the transmembrane electric field bring the defensin into the lipid bilayer

Question 26

where are cathelicidins stored and how are they released

Answer 26

stored in neutrophil granules as inactive precursors (prepropeptides
released when cleaved by neutrophil elastase

Question 27

what is the one cathelicidin gene (CAMP) identified in humans, codes for what peptide

Answer 27

LL-37

Question 28

what is LL-37 expressed in

Answer 28

lots of cells
circulating neutrophils, myeloid bone marrow cells
epithelial cells of skin and GI tract, epididymis and lungs