COMPLEMENT Flashcards
complex system composed of more than______ proteins.
30
• Aptly named because it complements the actions of______ and _______, enhancing the_________________
antibodies and phagocytic cells
body’s ability to recognize and eliminate threats to its health.
T or F
Complement
Present in an inactive form but become activated in response to various triggers.
True
• Once activated, the complement system sets off a cascade of ________that result in several crucial immune responses.
enzymatic reactions
GENERAL CHARACTERISTICS
• ________series of more than______ soluble plasma proteins
• Some are enzymes or proteinases
• Major fraction of______
• Part of the_______ component of the Innate I.S
• Participates in the________
Heat -labile ; 30
beta globulins
humoral
INFLAMMATORY RESPONSE
GENERAL CHARACTERISTICS
• Interacts in a specific way to enhance_______
• First described by_______; further studied by_______ and realize that the complement system was a complex cascade of proteins, and it was subsequently divided into pathways
host defense
Paul Ehrlichs
Jules Bordet
• Major role of complement
•
Promotes OPSONIZATION, CHEMOTAXIS and CELL LYSIS
NOMENCLATURE
• Named with a capital C and a number:
• Ex.
C1, C2…C9
NOMENCLATURE
• Small letter after the number:
• Ex.______
• Indicates that the protein is smaller portion of a large precursor as a result of_______ by proteases
C4b, C4a
cleavage
• Larger fragment: indicated by small letter “_____”
• Smaller fragment: indicated by small letter “_____”
b
a
NOMENCLATURE
Exception of the rule:
•______ fragments
• “a” fragment =_____
• “b” fragment =_____
C2
LARGER
SMALLER
There are____ major Complement components involve in the activation
9
COMPLEMENT
• Most are produced in the_____ Except:
•_____-produced by intestinal epithelial cells
•_____ - produced by adipose tissues
LIVER
C1
Factor D
: additional sources of: C1, C2, C3, and C4
• Macrophages and Monocytes
The rest of the components
• Acts as stabilizers and control proteins, and proteases.
ex.
Properdin, Factor H, Factor I
COMPLEMENT ACTIVATION
Involves three separate pathways:
CLASSICAL PATHWAY
ALTERNATIVE PATHWAY (a.k.a PROPERDIN PATHWAY)
MANNOSE-BINDING LECTIN (MBL) PATHWAY
CLASSICAL PATHWAY
The Recognition unit __________
________enzyme system
Stabilized by__________
C1 molecule (composed of C1q, C1r, C1s)
Interlocking enzyme system
Calcium ions
CLASSICAL PATHWAY
Requirement for Activation:
Antigen and Antibody Interaction
C’ binds to CH2 domain
All IgM can fix complement
All IgG can fix complement except IgG4
—Needs at least 2 monomers of lg attached to target cells
CLASSICAL PATHWAY
Recognition Unit
________ with _______ complex can recognize and bind to the Fc regions of these antigen-antibody complexes.
-C1q within the C1
Cleavage of…
Activated C1s cleaves complement components C4 and C2 into smaller fragments.
C4 and C2:
Formation of C3 Convertase_______
Activated C1s cleaves complement components C4 and C2 into smaller fragments.
(C4b2a)
Amplification and Cascade
-C3 bind to the pathogen’s surface and promote the formation of more…
C3 convertase complexes.
Formation of C5 Convertase______
-some C3b associates with C4b2a, forming C4b2a3b, also known as C5 convertase.
(C4b2a3b)
Further Activation
-cascade continues with the cleavage of C5; together with the bindings of_________, leading to the formation of the__________
C6, C7, C8, and C9
Membrane Attack Complex (MAC).
-The_______ creates pores in the pathogen’s membrane, resulting in cell lysis and destruction.
MAC
Formation of Membrane Attack Complex in details
-Recruitment of Complement Components:
complement components_________ are recruited sequentially to the site of C5b binding.
-Formation of the C5b-9 Complex
-Polymerization of C9
-Pore Formation
C6, C7, C8, and multiple units of C9
- Central Molecule of C’ Activation Pathways
C3
•______ is the major constituent of the complement system and is present in the plasma at a concentration of______
• Pivotal point for all three pathways,
C3
1200 g/mL.
• Cleavage of_______ represents the most significant step in the entire process of complement activation
C3 to C3b
