Complement Flashcards
20 or so proteins circulate in the – or – fluids in an – form. These are called —
Individual C proteins are activated by specific –
such as – and –/–
Proteolytic – of the —/— into 2 parts causes — of the protein.
Activation of each can activate the next, this is an example of a — reaction
serum tissue inactive proenzymes triggers infections immune complexes cleavage inactive protein activation cascade
C3a and C5a:
These are examples of —
They involved in (3)
Anaphylatoxins
cell activation
inflammation
chemotaxis
Opsonins:
Eg. – + –
They promote –
They also — immune complexes
C3b, C4b
phagoytosis
solubilize
C3B solubilizes –/– complexes and primes the – response.
AB, AG
secondary
Classical pathway: activated by --/-- complexes it uses -- so is part of the -- response Lectin + Alternative pathways: Involves --/-- and -- both of these are part of -- immune response
Ab-Ag antibody adaptive bacteria/fungi PAMPS innate
C3 is a — of the immune system
It plays a central role in the –/– and contributes to — immunity.
Its activation is required for both — and — complement activation pathways.
protein complement system innate classic alternative
What is opsonisation?
An immune process where particles are identified and targeted for destruction by phagocytes.
The membrane attack complex is a structure formed on the surface of –/– cells as a result of the activation of the (3) complement pathways. The MAC forms —/— channels which disrupts the –/– of the target cell
pathogenic bacterial classical alternative lectin transmembrane channels cell membrane
Classical Comlement Pathway:
Leads to complement activation via binding of – to –
Both the – and – antibodies are capable of initiating complement activation/
This initiation leads to recruitment of other proteins to form the C3 —/—/—.
This hydrolyses — resulting in further —/—
Antibodies Antigen IgM IgG convertase protein complex C3 complement activation
C3B fragments cleaves – into — and —
—, along with other complement proteins, forms the cylindrical —/—/— which leads to cell —
C5 C5a C5b C5b membrane attack complex lysis
Classical/Lectin pathways:
Immune complexes activate – to cleave – and – proteins which combine to make –/—. This is part of the — immune response.
In the — immune response, —/— activate host — which also cleave – and – to make —
C1 C4 C2 C3 convertase adaptive innate bacterial carbohydrates lectins C4 C2 C3 convertase
C3a stimulates — through the — activity
inflammation
chemoattractant
C3 can be cleaved into C3a or C3b, C3a is an example of a —, C3b is an example of a —
Anaphylatoxin
Opsonin
Activated C3b can combine with C3 convertase to make a –/–
C5 convertase
C5 convertase cleaves C5 in C5a, which is an —, and C5b which goes on to make part of the –/–/–
anaphylatoxin
major attack complex
Alternative pathway:
PAMPS can activate 2 factors in serum:
C3b combines with activated factors – and – to make an alternative type of –/–
Alternative –/– vastly increases the production of — by —/—
B + D B+D C3 convertase C3 convertase C3b \+ve feedback
Terminal Pathway:
C5b is deposited in — of —
C5b associates with (3) and extends across —/—
This complex polymerises — to make the —/—/— pore
membrane bacteria C6 C7 C8 cell membrane C9 Membrane attack complex
Membrane Attack complex:
C5b is rapidly — so it only binds to nearby —
inactivated
membranes
Complement disorders & Diseases:
Disorder: excess acivation. Outcome: —>
Disorder (deficiency in): Lectin pathway
Opsonin C3b
Classical pathway
Terminal pathway
Immune pathology Infant infections bacterial infections from birth tissue inflammation G-ve bacterial infections
Opsonisation:
This coats — and —/—
It enhances removal by —
Its also — complexes and stimulates — cells.
bacteria immune complexes phagocytes solubilizes B
Inflammation activates and attracts —
This activates — cells, this causes the release of — which causes —
phagocytes
auxillary
histamine
vasodilation
Regulation of MAC:
MAC inserts into any —/—, producing a trans-membrane —, allowing —
— proteins on our cell surface inhibit — of self cells.
Inhibitory — also exist in — to inactivate the —
— binds to and inactivates — to prevent membrane insertion.
cell membrane pore osmosis Inhibitory lysis proteins blood cascade Vitronectin C5b-C7