Humoral Effector Fxns

Question 1

CD64 ?

Answer 1

FC-gamma-RI
binds IgG1 and IgG3

on macrophages, neutros, eosinophils

activates phagocytes

Question 2

which IgG isotypes are the most efficient opsonins for promoting phagocytosis and what high affinity receptor do they act on

Answer 2

IgG3 and IgG1

Fc-gamma-RI (CD64) receptor

Question 3

what complement receptor on RBC binds immune complexes coated with C3b and C4b and transports this to liver/spleen

Answer 3

CR1

Question 4

binding of Ag to IgG allows binding of what of the classical pathway

Answer 4

C1q

Question 5

can IgE bind Fc receptors of eosinophils and mast cells without having Ag bound to its Fab portion?

Answer 5

YES

Question 6

what allows IgG to leave maternal blood and go to fetus

Answer 6

FcRn on RBC, Macrophages

Question 7

c5b67 complex of MAC can occur where

Answer 7

in fluid phase and on surface membrane

Question 8

what does properdin do in the alternate pathway

Answer 8

binds to C3bBb => C3bBbP and increases its half life

also stabilizes the C5 convertase: C3bBb3bP

Question 9

deficiencies in what 2 factors mimic C3 deficiency

Answer 9

Factor H and Factor I

Question 10

with a MAC deficiency you have an increase risk of infection by?

Answer 10

N. Gonorrhoeae

N. Menigitidis

Question 11

what is the most common complement deficiency

patients have a high degree of what?

Answer 11

C2
patients have a high degree of systemic lupus erthematosis SLE

-activates alternate pathway cuz lectin/classical pathway can’t work

Question 12

in complement regulation what is the first level of control of the convertases

Answer 12

decay acceleration
C3b hydrolysis limits C5 convertase
C4b hydrolysis limits C3 convertase

Question 13

C1 inhibitor (C1 INH) what does it do

Answer 13

binds C1r and C1s and dissociates them from C1q
controls classical/lectin pathway

removes MASP enzymes from MBL complex

Question 14

Factor I

Answer 14

cleaves C3b and C4b
co-factors: Factor H, MCP, C4BP, CR1

prevents formation of C3 and C5 convertases

Question 15

Factor H

Answer 15

binds C3b and displaces Bb

Question 16

C4-Binding protein (C4BP)

Answer 16

binds C4b and displaces C2

Question 17

Surface marker for Membrane cofactor Protein (MCP)

Answer 17

CD46

Question 18

DAF

Answer 18

displaces C2b from C4b; Bb from C3b

-> displaces C3 convertase AFTER its formed

Question 19

CD59 does what

Answer 19

blocks C9 binding on cell surface and prevents MAC formation

Question 20

what does Vitronectin (S protein ) do?

Answer 20

binds to fluid phase of C5b67 and prevents binding to membrane

Does NOT prevent association with C8 and C9 proteins