Structure And Function Of Complement System Flashcards
Structures that does Lysis require?
Ab— heat insensitive
Complement— heat sensitive
3 functions of complement system
1-Opsonization and phagocytosis
2-Complment-mediated cytolysis
3-Stimulation of inflammatory reactions
Which structures binds to microbe in order to opsonize
C3b
C4b
The ab-microbe + C3b complex is recognized by which receptor
CR1
Which formation occur in the Complement mediated cytolysis stage
MAC
How is the most circulating forms of complements
Inactive —> proenzymes or zymogens
Complement proteins synthesized in
Hepatocytes mostly
Tissue macrophages
Blood monocytes
Epi cells
Which cytokines induce the secretion of certain complement proteins
Acute phase proteins
TNF
IL-1
IL-6
IFN-y
3 activation of complement cascades
Alternative — no need for ab
Classical — ab
Lectin — Mannose
Activation of C3
C3 activation occurs by the cleavage of C3 to C3b and C3a
C3b for opsonization
C3a for inflammation
Alternative pathway is a part of the which immune system
Innate immune system
Formation of MAC
Initiated by C5 conversion to C5a and C5b
C5b binds C6
After then C7,C8,C9 binds and forms MAC
Initiation of Classical pathway dependent on
ab-ag interaction
Classical pathway is a part of which immune system
Adaptive immune system
Classical pathway ag-ab interaction causes
Activation of C1
For activation two heads of C1q must be simultaneously bound to the Fc region of IgG
Which abs in Classical pathway can bind C1
Abs that have bound to ag
IgM
IgG
Which type of Igs mostly activate the complement system at very high amounts
IgG1
IgG3
Which Ig type can not activate the complement system
IgG4
Lectin pathway is dependent of
Mannose binding lectin
Role of Vitronectin
Inhibits the lysis by prevents the binding of C9 to MAC
Roles of complement system
Cell lysis— MAC
Trigger inflammation- C3a, C5a
Attract phagocytes— C5a,C3b
Opsonise ag —C3b
Remove immune complexes—C3b
Activate naive B lymphocytes —C3b
Role of complement system in the Anaphylatoxins and inflammatory response
Binding of anaphylatoxins to G-protein coupled receptors stimulates the release of pro inflammatory mediators from cells
*C3a and C5a
Role of complement system in clearance of circulating immune complexes
Complement receptor of erythrocyte recognizes C3b by Fc
Bring it to Liver
Turn back to circulation
And phagocytosis occurs
Erythrocyte acts as a carrier
Tremendous amplification of anti-pathogen response due to
Formation of C3b
Complement activation promotes Clearance of pathogens and their products by
Opsonization
Immune complex clearance
Enhancement of ag presentation
Enhancement of B cell activation, memory and the generation of chemoattractant
