Lecture 3 - Complement System

Question 1

Important Regulatory molecules and CoFactors

Answer 1

1) Factor I - Degreased C3b and C4b
2) MCP - CoFactor for FI
3) Factor H CoFactor for C3 and C5 convertases
4) DAF - Destabilizes C3/C5 convertases in AP and CP

Question 2

FI-mediated C3b & C4b Inactivation

Answer 2

C3b and C4b degreased by FI and cofactors

Cofactors:
MCP
CR1
Factor H (C4BP in C4b degradation)

Mneumonic
C3b - Fine Men Can’t Hop
C4b - Fine Men Can’t Count

Question 3

C3 & C5 Convertase inactivation

Answer 3

Classical - DAF, CR1, C4BP
Alternative - DAF, CR1, Factor H

Mneumonic
Classical - Don’t Count Cards
Alternative - Don’t Count Fingers

Question 4

MAC inactivation proteins

Answer 4

CD59, S-protein, Victronectin

Can’t Stop Viagra

Question 5

Clinical Disease to Know

Answer 5

1) Glomerular diseases
2) Lupus nephritis
3) Vasculitis
4) Hereditary Angioedema
5) Paroxysmal Nocturnal Hemoglobinuria (PNH)

Question 6

Glomerular Injury

Answer 6

• Results for 1) Immune complex accumulation or 2) Abs binding to Kidney Ag
• Classical Pathway activated, regulatory proteins can’t stop due to acute inflammation

Question 7

Lupus nephritis

Answer 7

-Formation of lesions and fibrosis in glomerular tissue due to immune complex accumulation

Question 8

Vasculitis

Answer 8

• Blood vessel inflammation
  1) Immune dimple deposition
  2) Antibody interaction/attack

-Lupus erythematosus is associated with this

Question 9

Hereditary Angioedema

Answer 9

• HAE
• DEFECT in C1 Inhibitor (Inactivates C1r,s and MASPs)
  - Resuklts in CONSTANT complement response
• Edema (hands, feet, THROAT) - DEATH by ASPHYXIATION
• Abdominal pain

Bradykinin unregulated — increase vasopermeability and thus swelling

Question 10

Paroxysmal Noctural Hemoglobinuria (PNH)

Answer 10

• Can’t regulate MAC formation
  - GPI is deficient, can’t protect RBCs

Causes intravascular hemolysis — body blows up RBCs