Complement

Question 1

are there any cells involved in complement?

Answer 1

NO!!! just proteins

Question 2

what activates proteins in complement?

Answer 2

cleavage

Question 3

how are whole complement proteins denoted?

Answer 3

by C and a number

Question 4

when a complement protein is cleaved, how are its parts denoted?

Answer 4

use “b” to refer to the Bigger fragment and “a” to refer to the smaller fragment

Question 5

how are complement proteins classified?

Answer 5

by functional characteristics of the complement protein classes

Question 6

what are the 7 functional complement protein classes?

Answer 6

1. initiators
2. enzyme/convertase activators
3. opsonins
4. inflammatory mediators (anaphylatoxins)
5. membrane attack proteins
6. complement receptors
7. regulatory proteins

Question 7

what do initiator complement proteins do?

Answer 7

initiate the complement cascade

Question 8

what do enzyme/convertase activator complement proteins do?

Answer 8

they are enzymes that cleave other proteins, which are then activated and can have some enzymatic function

Question 9

what do opsonin complement proteins do?

Answer 9

mark things for phagocytosis

Question 10

what do inflammatory mediator (anaphylatoxin) complement proteins do?

Answer 10

increase blood flow to site of infection

Question 11

what is anaphylaxis?

Answer 11

too many anaphylatoxins (inflammatory mediator complement proteins)

Question 12

what do membrane attack complement proteins do?

Answer 12

make up the membrane attack complex

Question 13

what do complement receptor complement proteins do?

Answer 13

they are membrane-bound proteins that bind to other complement proteins and cause a response

Question 14

what do regulatory complement proteins do?

Answer 14

protect healthy host cells from the effects of complement

Question 15

what are the 3 complement activation pathways?

Answer 15

1. classical
2. lectin
3. alternative

Question 16

what was the first complement activation pathway discovered?

Answer 16

the classical pathway

Question 17

what activates the classical complement pathway?

Answer 17

activated by antigen-antibody complexes that bind to an initiator

Question 18

what activates the lectin complement pathway?

Answer 18

lectins bind to carbohydrate structures on bacterial cells

Question 19

are the lectins of the complement system the same as the lectin PRRs?

Answer 19

NO!! there are no cells in complement!!

Question 20

what activates the alternative complement pathway?

Answer 20

spontaneous cleavage of C3; no binding needed

Question 21

what are the 3 results from activation of any of the complement cascades?

Answer 21

1. membrane attack complex formation
2. opsonization
3. increase in inflammation

Question 22

what is the membrane attack complex (MAC)?

Answer 22

membrane attack proteins embed in bacterial cell membranes, forming a MAC

Question 23

what is the result of a membrane attack complex?

Answer 23

calcium from extracellular environment enters cell through the MAC, resulting in cell lysis

Question 24

describe opsonization (3)

Answer 24

1. complement protein binds to antigen
2. the complement protein will then bind to a complement receptor on a phagocytic cell
3. phagocytosis is initiated

Question 25

how does complement promote inflammation?

Answer 25

smaller complement fragments (a) bind to receptors and TNF-alpha and IL-6 are released, which also causes degranulation of granulocytes