Complement

Question 1

complement important in defense against which kind of organisms?

Answer 1

• pyogenic

Question 2

roles of complement

Answer 2

• promotes inflammatory response
• eliminates pathogens
• enhances immune response

Question 3

complement and immune complex diseases

Answer 3

• component in both prevention and pathogenesis of immune complex diseases

Question 4

functions of complement

Answer 4

• opsonization
• inflammation
• lysis

Question 5

opsonization

Answer 5

• attaches immune cells or antibodies to invading organism

- helps with phagocytosis by PMN/macrophages

Question 6

inflammation

Answer 6

• induces acute inflammation to dilate blood vessels
• activates mast cells/basophils
• recruits inflammatory phagocytic cells to eat invading organisms

Question 7

lysis

Answer 7

• generates a group of proteins to form membrane attack complex
• penetrate invading cell’s wall to induce lysis

Question 8

complement timing in immune response

Answer 8

• one of the earliest immune responses

Question 9

alternate complement pathway

Answer 9

• C3 -> C3b
• C3b -> C3bBb (C3 convertase) converts for C3 to C3b
• C3bBb3b (C5 convertase) converts C5 to C5b
• C5b interacts with C6-C9 to form membrane attack complex

Question 10

lectin pathway

Answer 10

• C1-like complex converts C4 to C4b
• C4b interacts with C2b from classical pathway to form C4b2b (C3 convertase)
• Converts C3 to C3b
• forms C4b2b3b (C5 convertase) converts C5 to C5b
• C5b interacts with C6-C9 to form membrane attack complex

Question 11

classical pathway

Answer 11

• C1 present
• converts C2 to C2b
• C2b interacts with C4b from lectin pathway to form C4b2b (C3 convertase)
• Converts C3 to C3b
• forms C4b2b3b (C5 convertase) converts C5 to C5b
• C5b interacts with C6-C9 to form membrane attack complex

Question 12

starting points of alternative pathway

what branch of immune system

Answer 12

• C3
• factor B, D
• properdin
• innate immune system

Question 13

starting points of lectin pathway

what branch of immune system

Answer 13

• plasma-derived mannose-binding lectin
• MBL
• innate immune system

Question 14

starting points of classical pathway

what branch of immune system

Answer 14

• C1qrs
• C2
• C4
• adaptive immune system

Question 15

trigger start of alternative pathway

Answer 15

• complement components bind on microbial surfaces and cannot be turned off
• SPONTANEOUS

Question 16

trigger start of lectin pathway

Answer 16

• MBP normally exists in circulation
• MBP binds to mannose on bacterial surface
• produces enzyme to cleave C4 into C4b and C2 into C2b

Question 17

trigger start of classical pathway

Answer 17

• interaction of Fc portion of antibody
  
  • IgM
  • IgG1, IgG2, IgG3
• c reactive protein with C1q

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Question 18

why can complement components not be turned off by microbes?

Answer 18

• their regulatory proteins only exist on host cells, not microbial surfaces

Question 19

common goal of all three pathways

Answer 19

• make C3b

- deposit C3b on clusters on the target

Question 20

which acts as an opsonin?

How does it act as an opsonin?

Answer 20

• C3b
• C3b recognized by complement receptor type 1 on phagocyte
• microbes phagocytosed

Question 21

which are the anaphylaxotoxins

Answer 21

• C3a, C4a, C5a

think A causes Anaphylaxis

Question 22

which are the chemoattractants?

Answer 22

• C3a, C5a

Question 23

what do the anaphylatoxins do?

Answer 23

• increases vascular permeability to enhance movement of leukocytes and plasma proteins into tissues

Question 24

do you chemoattractants do?

Answer 24

• attract neutrophils and monocytes for destruction of pathogen

Question 25

how does the membrane attack complex kill cells?

Answer 25

- creates perforations in cellular membranes | - induces osmotic lysis of cells

Question 26

what is the membrane attack complex effective against?

Answer 26

- microbes with thin cell walls (gram negatives) | - Neisseria species

Question 27

decay accelerating factor (DAF) function

Answer 27

- down regulates C3 convertase | - displaces Bb from C3b

Question 28

DAF deficiency

Answer 28

- also known as CD55 deficiency - uncontrolled complement activation that leads to RBC lysis - leads to paroxysmal nocturnal hemoglobinuria

Question 29

C1 inhibitor

Answer 29

- protease inhibitor - down regulates C1r and C1s activation in classical pathway - prevents complement activation on self cells

Question 30

C1 esterase inhibitor deficiency

Answer 30

- uncontrolled C1 activation - leads to excessive vasoactive peptides being generated - leads to hereditary angioedma

Question 31

why C1 inhibitor deficiency can lead to hereditary angioedema

Answer 31

- unrelated activation of kallikrein to bradykinin

Question 32

role of bradykinin

Answer 32

- vasodilation and increases vascular permeability | - ergo edema

Question 33

what characterizes C1 esterase inhibitor deficiency

Answer 33

- low C4 levels | - high bradykinin

Question 34

C3 deficiency

Answer 34

- risk of encapsulated bacterial infection | - recurrent pyogenic infections

Question 35

C5b-C9 deficiencies

Answer 35

- increased susceptibility to Neisseria infections | - severe pyogenesis and sepsis in infants

Question 36

C1, C2, C4 deficiency

Answer 36

- associated with immune complex disorders | - especially SLE