Complement System Deficiencies

Question 1

Classical Pathway Deficiencies (early components)

Answer 1

CP responsible for clearing immune complexes, apoptotic cells and cell debris

C1, C4, C2 deficiencies = recurrent sinopulmonary infections, Rheumatoid arthritis

Question 2

Classical Pathway Deficiencies (C3)

Answer 2

-Results in similar phenotype as –Ab deficiencies but is less frequent than ab immunodeficiencies

Question 3

Classical Pathway Deficiencies (Late components)

Answer 3

• Defects with C5-C9 and thus MAC

- Susceptibility to Neisseria meningitis

Question 4

Alternative Complement Pathway Deficiencies

Answer 4

-Properdin, Factor B, Factor D
(Alternative Complements Make People Fuck Friends)
-Infections from Neisseria meningitis

Question 5

Factor H Deficiency

Answer 5

Hemolytic uremic syndrome - destruction of blood platelets

Factor H = H for Hemolytic

Question 6

C1-INH Inhibitor Deficiency

Answer 6

• Hereditary Angioedema
• Results from overproduction of bradykinin, which increases vascular permeability and lets fluid into the tissues
• Treatment: inhibitor replacement therapy

Question 7

C8 Complement Deficiencies

Answer 7

• Late complement protein deficiency

- INVASIVE NEISSERIAL INFECTIONS

Question 8

Hereditary Angioedema (HAE)

Answer 8

• Recurrent swelling of hands, face, neck, etc that can cause ASPHYXIATION from swelling
• Not complement enzyme but Bradykinin-Kinin pathway from C1-INH Inhibition

Question 9

Paroxysmal Nocturnal Hemoglobinuria (PNH)

Answer 9

• Defect in glycosylphosphatidylinositol
• Can’t regulate MAC formation
• DAF and CD59 essential for protection — lack of them leads to hemolytic anemia

Question 10

TLR Deficiencies

Answer 10

• Defect in MyD88
  
  • Affects all TLRs (except TLR3)
• Frequent infections from pyogenic bacteria but not common pathogens (bacteria, viruses, fungi, etc.)
• NO FEVERS since signal transduction to release TNF, IL-1 and IL-6 does not occur