Fc Receptors
True or False: FcERI is expressed on eosinophils
FALSE
Mannose-binding lectin-associated serine protease
Lectin
True or False: requires IgG or IgM for activation
FALSE
The most efficient IgG antibody activators of complement
IgG1 and IgG3
Deficiency of C1q
HAE
What is the high affinity Fc receptor that binds IgG1 and IgG3
RcgRI
C1
Classical
Activated C3 binds this protein to form the C3 convertase
Factor B
True or False: Only antibody-antigen complexes (not free antibodies) activate the classical pathway
True
Deficiency of DAF (decay accelerating factor)
What Fc Receptor provides feedback inhibition of cellular responses
RcgRIIB (CD32)
C3bBb
Alternative
Binds to the surface of the microbe - acts as an opsonin and a component of C3 and C5 convertases
C3b
This cleaves C4 to generate C4b
Activated C1s
Absence of CR3 and CR4 (shared by CD11/CD18 integrins)
LAD
This Fc receptor is required for ADCC (NK cells)
FcgRIIIA (CD16)
C5 convertase
Cleaves factor B when bound to C3b
Factor D
C3 in the alternative pathway is homologous to ___ in the classical pathway
C4
Most common mutations in HUS
Factor H
The low affinity FcERII (CD23) is found on these cells
B cells, eosinophils, Langerhans cells
Factor D
Alternative
Stabilizes C3bBb on microbial surfaces
Properdin
The components of C5 convertase
C4b2a3b
While Factor B and D deficiencies are rare, this deficiency in the alternative pathway is X-linked and more common
X-linked properdin deficiency