Shared Flashcard Set

Details

Complement System
my head hurts
47
Immunology
Undergraduate 4
03/04/2015

Additional Immunology Flashcards

 


 

Cards

Term
What proteins in the horseshoe crab are homologous to vertebrate complement proteins?
Definition
hemolymph
Term
What types of molecules can activate the vertebrate complement system?
Definition
PAMPs
antibodies + microbial antigens
coagulation/fibrinolytic components
Term
What does the MAC do?
Definition
punches holes in the microbial cell membranes, resulting in osmotic lysis
Term
What are the 3 complement pathways?
Definition
Alternative Pathway
Lectin-Binding Pathway
Classical Pathway
Term
Which are the oldest complement genes?
Definition
C3 & Factor B (Bf)
Term
Duplications of C3 led to...
Definition
C4 & C5
Term
Duplication of Bf led to....
Definition
C2
Term
The classical pathway developed as a result of...
Definition
duplication events leading to C6,C7,C8 & C9
Term
Chickens lack the complement genes for...
Definition
C2, C9, MASP1, Factor P (properdin)
Term
Zebrafish lack the complement genes for...
Definition
MASP1 & Ficolin
Term
Which complement proteins are produced by the liver?
Definition
C3, C6, C8, Bf
Term
Which complement proteins are produced by macrophages?
Definition
C2-C5, Bf, Df, Pf, If
Term
Neutrophils are capable of producing & storing...
Definition
C6 & C7
Term
Host cells are rich in sialic acid, allowing _____ to bind to C3b
Definition
Factor H (Hf)
Term
What happens to C3a produced by the spontaneous degradation of C3 in the alternative pathway?
Definition
degraded by chymase
Term
Which complement receptors is iC3b able to bind to?
Definition
CR1
CR3
CRIg
Term
Describe the construction of an anchor molecule
Definition
1. C5 binds to C3b on microbial cell surfaces
2. C3bBb or C4bC2b cleaves C5
3. C5a is released into humoral fluid
4. C6 & C7 bind to C5b forming C5b67
5. Complex formed is inserted into membrane
Term
Describe the assembly of the MAC
Definition
C8 & C9 bind to C5b67 complex
MAC is created, acting as a pore which inhibits osmotic regulation of the microbial cell
Term
What activates the lectin-binding pathway?
Definition
MBL or ficolins bind to microbial cell wall, activating a MASP2 complex
Term
MASP2 is critical for the lectin-binding pathway and also...
Definition
thrombin activation
Term
What activates the classical pathway?
Definition
IgM or IgG produced during the acquired immune response attach to the microbial surface, resulting in a conformational change which exposes the Fc region of the antibody
(the Fc region contains complement-binding sites)
Term
What is the most important regulator of the classical pathway? What does it do?
Definition
C1-INH
-blocks C1r & C1s, preventing C4bC2b assembly
Term
What proteins are able to accelerate the decay of C3 & C5 convertases?
Definition
CD55
Hf
If
C4-binding protein
CR1 (CD35)
Term
Which proteins block the insertion of of C5b678 into the microbial cell mmb?
Definition
vitronectin
clusterin
CD59 (protectin)
Term
What ligands does CR1 bind? What effect does their binding have on the immune response?
Definition
C3b
C4b
iC3b

-allows the complexes to be removed by the spleen & liver
Term
Where are CR1 receptors found in primates?
Definition
90% are on RBCs
10% are on phagocytic cells
Term
What ligands does CR2 bind? What effect does this have?
Definition
C3d

-CD19/CR2 complex is formed, releasing a signal to increase activation of B cells in response to microbial presence
Term
What ligands does CR3 bind? What effect does this have?
Definition
iC3b

-mediates phagocytosis & cytotoxicity
Term
What ligands does CR4 bind? What effect does this have?
Definition
breakdown products of C3

-mediates phagocytosis, cytotoxicity, clotting
Term
Where are C3aR & C5aR found? What happens when they bind to C3a and C5a?
Definition
mast cells
eosinophils
basophils

degranulation, release of vasoactive compounds
Term
What ligand does C1qR bind? What effect does this have?
Definition
C1q

-mediates phagocytosis of apoptotic bodies
-mediates macrophage differentiation
-mediates DC migration
Term
What ligands does CRIg bind? What effect does this have?
Definition
C3b & iC3b

phagocytosis of pathogens in the blood
Term
Where is CRIg found?
Definition
tissue macrophages e.g. Kupffer cells
Term
C1q can act as an opsonin for...
Definition
apoptotic bodies
Term
C3b & C4b can act as opsonins for.....
Definition
phagocytic cells
Term
Which complement proteins have vasoactive properties?
Definition
C2a
C3a
C5a
Term
What are the anaphylactic effects of C3a & C5a? (5)
Definition
-mast cell/eosinophil degranulation
-platelet release of vasoactive compounds
-increased vascular permeability
-neutrophil release of lysosomal enzymes
-macrophage release of thromboxane
Term
Which C3 breakdown product is bacteriolytic?
Definition
C3a
Term
What causes BLAD in cattle?
Definition
SNP in CD18 reduces B2 expression, preventing leukocyte adhesion
Term
What causes glomerulonephritis?
Definition
SNP in Hf leading to excess C3b being deposited in the kidneys
Term
SNPs in which complement genes increases the risk of asthma?
Definition
C3
C5
C5aR
C3aR
Term
Which component of the coagulation-fibrinolysis process acts strictly as a C3 convertase?
Definition
kallikrein
Term
Which components of the coagulation-fibrinolysis process act as C3 & C5 convertases?
Definition
Factors X, XI, IX
thrombin
plasmin
Term
How does Streptococci M affect complement activation?
Definition
masks C3b binding sites, preventing opsonization
Term
How does Staph aureus affect complement activation?
Definition
produces fibrinogen-binding protein which changes the shape of C3b, preventing interaction with Bf
Term
How does Salmonella enterica affect complement activation?
Definition
Rck gene prevents MAC from being inserted into bacterial mmb
Term
How does E coli affect complement activation?
Definition
produces Stx which activates the complement system
-binds to Hf, downregulates CD59 in kidney cells, increases C3b production
-MACs on renal cells lead to hemolytic uremic syndrome
Supporting users have an ad free experience!