Complement

Question 1

MASP-2

Answer 1

Mannan binding lectin-Associated Serine Protease 2

Question 2

Function of MASP-2

Answer 2

Cleaves C4 and C2 (into C4a and b, C2a and b)

Question 3

Function of MASP-2

Answer 3

Cleaves C4 and C2 (into C4a and b, C2a and b)

Question 4

Three activation pathways of the complement system

Answer 4

Classical (antigen/antibody complexes)
Lectin (lectin binding to pathogen surfaces)
Alternative (pathogen surfaces on microorganisms)

Question 5

Site of complement activation

Answer 5

Surface of antigens

Question 6

Site of complement activation

Answer 6

Surface of antigens

Question 7

Common convergence of activation pathways

Answer 7

Cleavage of C3 by C3 convertase. Leaves C3b bound to the microbial surface and releasing C3a

Question 8

Overview of lectin pathway

Answer 8

MBL and ficolins recognize/bind carbohydrates on pathogen surface.

Involves C4 and C2. MASP-2 cleaves C4 and C2.

Question 9

Overview of classical pathway

Answer 9

C1q interacts with pathogen surface/antibodies on the surface

C1q, C1r, C1s lead to C4 and C2 activation via cleavage

Question 10

Overview of alternative pathway

Answer 10

Takes place on surface of microorganisms. C3 undergoes spontaneous hydrolysis to C3(H2O) to initiate eventual deposition of C3 convertase

Involves factor D, factor B, properdin, and C3

Question 11

Number of IgG molecules required for binding to C1q

Answer 11

2

Question 12

Number of IgM molecules required for binding to C1q

Answer 12

1 (pentameric form)

Question 13

Overview of classical pathway

Answer 13

C1q interacts with pathogen surface/antibodies on the surface

C1q binds, C1r undergoes conformatinoal change and becomes active, C1r then cleaves and activates C1s

Leads to C4 and C2 activation via cleavage

Question 14

Number of IgM molecules required for binding to C1q

Answer 14

1 (pentameric form, multiple binding domains)

Question 15

Number of IgM molecules required for binding to C1q

Answer 15

1 (pentameric form, multiple binding domains)

Question 16

Requirement for the activation of C1qrs complex

Answer 16

At least two of the C1q heads must be simultaneously bound to antibody