Chapter 5 - Complement System Flashcards
He was the first to elucidate the complement system.
Jules Bordet
He coined the term “complement” because these proteins “complements” antibodies to cell lysis.
Paul Ehrlich
Which is usually the bigger fragment, a or b?
Fragment b
The complement that is exempted from the rule that the fragment b is bigger than fragment a.
C2
Which is bigger, C2a or C2b?
C2a
The complement number is based on?
Its order of discovery
Trimolecular complex of q, r and s.
C1
The q, r and s of C1 in the classical pathway are connected by?
Calcium
Most abundant complement protein.
C3
The complement which has the highest molecular weight
C1
Complement proteins when subjected to electrophoresis are found at which region?
Beta
Complement proteins are synthesized by which organ?
Liver
Besides the liver, some complements can be synthesized by other parts of the body. Which body parts are these and which complement can they produce?
Intestinal epithelial cells - C1
Adipose - factor D
The first complement pathway to be described.
Classical pathway
The classical pathway is initiated by?
2 IgGs and 1 IgM
Recognition unit of the classical pathway
C1 (C1q, C1r and C1s)
Activation units of the classical pathway
C2, C3, C4
Membrane attack complex (MAC)
C5 to C9
C3 convertase in the classical pathway
C4b2a
C5 convertase
C4b2a3b
The end result of the complement system.
Cell lysis
Also known as the bypass pathway.
Alternative pathway
The alternative pathways starts with which complement?
C3
Activating substance for the alternative pathway.
LPS (bacterial capsule), IgA
In the alternative pathway, the C3-C5 convertase is stabilized by?
Properdin
The recognition unit for the alternative pathway
C3, factor B, factor D
C3 convertase in the alternative pathway
C3bBbP
C5 convertase in the alternative pathway
C3bBb3bP
True or False: C3 is present in all pathways.
True
Which complement proteins are not present in the alternative pathway?
C1, C2, and C4
Which complement protein/s is/are not present in the lectin pathway?
C1
The recognition unit for the lectin pathway
MASP-1, -2, -3
Activating substance in the lectin pathway
Mannose group on microbial cell
Which electrolyte is necessary for the lectin pathway?
Calcium
Which electrolyte is necessary for the alternative pathway?
Magnesium
Which electrolyte is necessary for the classical pathway?
Calcium
C3 convertase of the lectin pathway.
C4b2a
C5 convertase of the lectin pathway.
C4b2a3b
Complement pathway that is also known as the properdin pathway.
Alternative pathway
Major regulator of the classical pathway.
C1 inhibitor
Cleaves C3b and C4b
Factor I
Cofactor with Factor I to inactivate C3b; prevents binding of B to C3b
Factor H
Acts as a cofactor with factor I to inactivate C4b
C4 binding protein
Major regulator of the alternative pathway.
Factor factor H
Prevents attachment of the C5b67 complex to cell membrane.
S protein
Accelerates dissociation of C3 convertase.
Decay accelerating factor (DAF)
The disease associated with patients without DAF.
Paroxysmal nocturnal hemoglobinuria
Blood group associated with DAF.
Cromer
CD receptor for DAF
CD55
It prevents bystander lysis of red cells.
DAF
It prevents insertion of C9 into the cell membrane.
MIRL
CD receptor for MIRL.
CD59
Most common complement deficiency.
C2 deficiency
Complement deficiency associated with severe recurrent infections and glomerulonephritis.
C3 deficiency
Complement deficiency associated with Neisseria syndrome, meningitidis and gonorrhoea
C5-C8
Complement deficiency with no known associated disease.
C9 deficiency
Deficiency in this complement regulator is associated with hereditary angioedema (HAE or HANE)
C1 inhibitor
Deficiency in this complement regulator is associated with recurrent pyogenic infection.
Factor H or I
Most commonly measured complement protein.
C3b
Assay in measuring the activity of the complement components of the classical pathway.
CH50 assay
Assay in measuring the activity of the complement components of the alternative pathway.
AH50 assay
What does the 50 in CH50 and AH50 assay indicate?
50% is used because this is when the change in lytic activity per unit change in complement is at maximum.
Which is more clinically significant, elevated or decreased complement components?
Decreased complement levels
Enumerate the inhibitors of MAC
MIRL (CD59), HRF
Traditional test to differentiate between N. meningitidis from N. gonorrhoea.
Carbohydrate utilization test
Deficiency on this complement component is associated with pneumococcal diseases, sepsis and Neisseria infections.
MBL
Deficiency on this complement component is associated with pneumococcal diseases.
MASP-2
Deficiency on this complement component is associated with Neisseria infections.
Properdin
What is detected in the complement fixation test?
Complement-fixing antibody
How is complement fixation test reported?
Highest dilution without hemolysis
Positive result in complement fixation test
Red cells not lysed
Negative result in complement fixation test
Red cell lysis
Where do you get the red cell used for complement fixation test?
Sheep’s RBC
Where do you get the complement proteins present in complement fixation test?
Guinea pigs
2 systems involved for complement fixation.
Test system / bacteriolytic system and indicator system / hemolytic system