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Immune System - Innate 2
Complement System 11/15/10
52
Medical
Professional
11/16/2010

Additional Medical Flashcards

 


 

Cards

Term

 

- Inactivated by heat

- couples the recognition of antigen by antibodies to a desired biological event

- series of over 30 different serum and membrane proteins (usually inactive)

- do not increase upon immunization

Definition

 

Complement

Term

 

- made up of a "cascade" --> activation of one component leads to activation of the next component

- rapid amplification, yet relatively unstable

- synthesized in MHC and Hepatocytes

Definition

 

Complement

Term

 

- complement reactions all occur on cell surface

- initial components attach to cell, which activates it

Definition

 

Fixation

Term

 

- the inactive form of complement components that circulate in blood

Definition

 

Proenzymes

Term

 

- abbreviation of complement

Definition

 

C'

Term

 

- usually the smaller fragment of complement

- usually associated with inflammation

- can be anaphylotoxins (stimulate inflammation)

- when bound, release histamine

Definition

 

'a' complement fragment

Term

 

- ions required to activate complement

Definition

 

Ca & Mg

Term

 

- the bond by which C3b attaches to the pathogen cell surface

Definition

 

high-energy thioester bond

Term

 

- product of all three complement activation pathways

- results in C3b complement fixation to pathogen surface

Definition

 

C3 Convertase

Term

 

- first complement pathway to act

- does not require the presence of pre-existing antibodies

- starts in solution and moves to pathogen surface

- produces active C3b

Definition

 

Alternative Pathway

Term

 

- in Alternative Pathway this complex functions as a C3 Convertase

- created from binding of Factor B

Definition

 

iC3Bb

Term

 

- breaks the thioester bond of C3 to form iC3

Definition

 

water

Term

 

- a protease that cleaves B into Ba and Bb while it is bound to iC3

Definition

 

Factor D

Term

 

- feedback from C3b being created by C3bBb in a cycle that proceeds on the pathogen surface that amplifies the response

Definition

 

Positive Feedback Process

Term

 

- when a pathogen is well-coated by C3b

Definition

 

opsinin

Term

 

- activated when C3bBb combines with another C3b to form C3b2Bb

Definition

 

C5 Convertase

Term

 

- stabilizes C3bBb on microbial surface

- works against Factors H and I

Definition

 

Properdin (Factor P)

Term

 

- makes C3b susceptible to cleavage by Factor I

Definition

 

Factor H, MCP

Term

 

- a lack of this factor depletes the level of C3 in blood, extracellular fluid and lymph --> clearance of infection less effective

Definition

 

Factor I

Term

 

- after binding to C3b part of convertase --> causes dissociation and inactivation

Definition

 

DAF

Term

 

- DAF, MCP, Factor H make up this family

Definition

 

RCA (regulators of complement activation)

Term

 

- activated after the alternative pathway

- triggered by inflammation--> production of acute-phase proteins

Definition

 

Lectin Pathway

Term

 

- proteins that bind carbohydrates

- MBL is one example that binds Mannose

Definition

 

Lectin

Term

 

-protein that is responsible for triggering the classical pathway (without antibody binding)

Definition

 

C-reactive protein

Term

 

- binds to mannose residues of glycoproteins or carbohydrates on the surface of microorganisms

- MASP then binds it

- looks like a bunch of flowers with stems

 

Definition

 

MBL

Term

 

- number of molecules of MASP-1 and MASP-2 that bind MBL after it binds to microorganisms

Definition

 

two

Term

 

- cleaves C4 into its 'a' and 'b' fragments in Lectin Pathway

Definition

 

MASP-2

Term

 

- binds to C4b and is then cleaved by MASP-2

- the 'a' fragment stays bound

Definition

 

C2

Term

 

- the C Convertase complex in the Lectin pathway

- can cleave C3 to create a C5 Convertase

Definition

 

C4bC2a

Term

 

- the antibodies that activate complement

 

Definition

 

IgM and IgG

Term

 

- due to pentameric structure, the most efficient antibody for complement activation

- only one molecule required to do so

Definition

 

IgM

Term

 

- starts when an antibody directed against a protein binds to the surface of that cell or with CRP

- last pathway to respond

Definition

 

Classical Pathway

Term

 

- first component of complement to bind in classical pathway

Definition

 

C1q

Term

 

- functions similarily to MASP-2 in the classical pathway

- looks like an S when free, like a figure 8 when bound to C1q

Definition

 

Cr2s2

Term

 

- binding of C1q to the antibody molecules activates this complement

Definition

 

C1r

Term

 

- activated by C1r by cleavage

- cleaves C4 to allow C4b to bind to target surface

Definition

 

C1s

Term

 

- inhibits activation of C1

- an insufficiency leads to inappropriate release of C2b which can produce leaky vessels and hereditary angioedema

Definition

 

C1-Inh

Term

 

- binds C4bC2a and increases the sensitivity of C4b to Factor I

Definition

 

C4bp

Term

 

- functions similar to C4bp on the surface of cells

Definition

 

CR1 & MCP (membrane cofactor protein)

Term

 

- dissociates C4bC2a

Definition

 

DAF (decay accelerating factor)

Term

 

- the two C3 Convertases that C3b can bind to

Definition

 

C3bBb & C4bC2a

Term

 

At what number C complex does the MAC undergo a conformational shift and insert itself into the membrane?

Definition

 

7

Term

 

- several of tis complement create a pore in the membrane after C5b678 bores deeper into the membrane

Definition

 

C9

Term

 

- prevent C5b67 from associating with cell membranes

Definition

 

S Protein

Clusterin

Factor J

Term

 

- prevent recruitment of C9

Definition

 

HRF (homologous restriction factor)

CD59 (protectin)

Term

 

-components of complement system are extremely labile

- previous substrate midification

- specific regulatory proteins act on the 3 pathways

Definition

 

Regulators of the Complement System

Term

 

- important effector of humoral immune response

- particularly can target gram negative bacteria (w/ lysozyme)

Definition

 

Cell Lysis

Term

 

- macrophages and neutrophils recognize the complement coat which enhances phagocytosis and degradation

Definition

 

opsonization

Term

 

- vasoactive and allows fluid to move from the blood vessels into the tissues

Definition

 

C2b

Term

 

- have receptors for C3b

- carry immune complexes to spleen where they can be phagocytosed and degraded

Definition

 

Erythrocytes

Term

 

- comes from a lack of necessary comlement components that leads to high levels of immune complexes that can lead to tissue damage

- defects in C1, C4 or C2

Definition

 

Lupus (SLE)

Term

 

- comes from a defect in the anchoring proteins for DAF, HRF and CD59

- host's blood cells become more sensitive to complement which leads to lysing

Definition

 

Paroxysmal Nocturnal Hemoglobinurea (PNH)

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