Lecture 5 - Complement System

Question 1

When complement is activated, what happens?

Answer 1

opsonization, pro-inflammatory, chemotaxis, eliminate bacteria/microbes

Question 2

What is the complement sys?

Answer 2

A cascade of protein molecules that acts as an alarm & a weapon against infection, especially bacterial infection. Has the capacity to lyse cell membranes to microbes.

Question 3

What are the 3 modes of activation of the complement system?

Answer 3

1) Classical pathway
2) Alternate or properdin pathway
3) Mannose-binding protein

Question 4

What activates the classical pathway?
The alternate or properdin pathway?
The mannose-binding protein?

Answer 4

Antigen or antibody complex
Bacteria and their products binding to lectins (ex. C3b/factor B or D)
The binding of sugars on the bacterial cell.

Question 5

The three activation pathways of complement converge at a common _____________, the activation of the __ component. Then, _________ of pathogens, _____ of pathogens or __________ of inflammatory cells occur.

Answer 5

junction point; C3; opsonization; killing; recruitment

Question 6

The complement reaction starts with an __________. Complement components are designated by numerals (_____).
C1-C9 is activated by __________, then will be designated as “__” fragment and/or “__” fragment

Answer 6

enzyme cascade; C1-C9; cleavage; a; b

Question 7

In the classical pathway there are 2 antibodies that can be involved: ________. They are able to bind _____ and then undergo a change that allows _________ to bind (conformation change).

Answer 7

IgG or IgM; antigen; complement

Question 8

Classical pathway: C4b and C2b is referred as ___________. When you add C3b to C4b + C2b complex, it produces ___.

Answer 8

C3 convertase; C5

Question 9

The alternate pathway is activated directly by ________________ and their components (e.g., ________, ________________), as well as other factors.

Answer 9

bacterial cell surfaces; endotoxin; microbial polysaccharides

Question 10

The initial activation of the alternate pathway is mediated by __________ binding to ___ and then with properdin factor __, which splits factor __ in the complex to yield the __ active fragment that remains linked to ___ (activation unit).

Answer 10

properdin factor B; C3b; D; B; Bb; C3b