complement + complement disorders

Question 1

hereditary angioedema

Answer 1

deficiency of C1 esterase inhibitor → ↑ bradykinin

Question 2

drugs to avoid if have hereditary angioedema

Answer 2

ACEi: also ↑ bradykinin → angioedema is a SE

Question 3

recurrent pyogenic sinus infections and respiratory tract infections:
S. pneumoniae
H. influenzae
↑ type III HSR susceptibility: glomerulonephritis

Answer 3

deficiency of C3

Question 4

Neisseria bacteriemia (gonococcal, meningococcal)

Answer 4

deficiency of any of MAC complement proteins: C5b, C6, C7, C8, C9

Question 5

paroxysmal nocturnal hemoglobinuria (complement mediated RBC lysis)

Answer 5

deficiency of decay accelerating factor (DAF, CD55, protects own cells from complement that has spontaneously activated itself via alternate pathway)

Question 6

RBCs deficient in 2 surface molecules that protect against the MAC:
glycosylphosphoinositol (GPI) anchors DAF (CD55) to plasma membrane
MAC-inhibitory protein (CD59)
results in complement mediated RBC lysis → chronic intravascular hemolysis, hemosiderinuria (Hb in urine = RED COLOR urine), thrombosis (platelets desroyed too and release prothrombotic contents)

Answer 6

paroxysmal nocturnal hemoglobinuria (PNH)

Question 7

diagnosis of PNH

Answer 7

Ham’s test: put RBC in acid → if lyse at low pH = positive for PNH
flow cytometry: look or CD59 or CD55 on RBC

Question 8

treatment of PNH

Answer 8

transfusions: chronic hemolysis
warfarin: risk of thrombosis
eculizumab: inhibits complement, prevent attack on RBCs (expensive)

Question 9

responsible for mast cell + basophil stimulation

Answer 9

C3a

Question 10

responsible for neutrophil chemotaxis

Answer 10

C5a

Question 11

responsible for opsonization

Answer 11

C3b + IgG

Question 12

components of MAC

Answer 12

C5b
C6
C7
C8
C9

Question 13

IL-12 receptor deficiency is at increased risk for

Answer 13

mycobacterial infections