Download - Effector mechanisms of humoral immunity
Effector mechanisms of humoral immunity
The Complement System
(C’)
Activation pathwaysEffector functions
Regulation of complement activation
Jules Bordet(1870-1961)
1919.
Nobel prize
For complement-mediated bacteriolysis
Complement system(complements i.e. assists functions of antibody)
Consists of serum and cell surface proteins involved in defense against pathogens and tissue damage mediated by antibodies
Effector mechanism of both innate and adaptive humoral immunity
Complement system
Over 30 serum and cell surface proteins:
- Complement components (in serum inactive, activated sequentially as a cascade)
- Complement receptors(cell surface, recognize activated components)
- Regulatory proteins of complement(both in serum and cell surface, inhibit activated
components)
Complement system
Classical
Lectin
Alternatve
C1, C4, C2
Early steps Late steps
MBL, C4, C2
C3, B, D (P)
C3, C5, C6, C7, C8, C9
C3, C5, C6, C7, C8, C9
C3, C5, C6, C7, C8, C9
Activationpathway
Classical
Lectin
Effector functions(elimination of pathogen)
C3 convertase
Alternatve
Ag-Ab complex(microorganism and IgG or IgM Ab)
microorganism
microorganism
C5 convertase
b
a
Early steps Late steps
C1
MBL
C3
C4
C2
D
B
Late steps of complement activation
C1C1Activated
C4b2b
C3 CONVERTASE
C5
C9C8C7C6
Bacterium
IgG
IgM
C4 C2C4a C4bC2b C2a
C3
C3aC3b
C4b2b3b
C5 CONVERTASE
C5a C5bLysis
MEMBRANE ATTACK
COMPLEX
C5-C9 MAC
C4b2b
C3 CONVERTASE
C5
C9C8C7C6
Bacterium
C4 C2C4a C4bC2b C2a
C3
C3aC3b
C4b2b3b
C5 CONVERTASE
C5a C5bLysis
MEMBRANE ATTACK
COMPLEX
C5-C9 MAC
MASP
MBL
C3 C3b
C5
C6C7C8C9
Bacterium Factor D
Ba Bb
C3
C3a C3b
C3bBb3b
Alternative C5 convertase
C5b
C5a
Lysis
MEMBRANE ATTACK
COMPLEX
C5-C9 MAC
Factor B
C3bB C3bBb
Alternative C3 convertase
Properdin
Effector functions of activated complement
- Cytolysis (MAC)
- Opsonization (C3b, C4b)
- Stimulation of inflammation (C5a, C3a, C4a)
Stimulation of inflammatory rections
(C5a, C3a, C4a) Activation of mast cells and neutrophils
(anaphylatoxins)
Effector functions of activated complement
- Cytolysis (MAC)
- Opsonization (C3b, C4b)
- Stimulation of inflammation (C5a, C3a, C4a)
- Stimulation of humoral response (C3d)
Effector functions of activated complement
- Cytolysis (MAC)
- Opsonization (C3b, C4b)
- Stimulation of inflammation (C5a, C3a, C4a)
- Stimulation of humoral response (C3d)
- Immune complex clearance (C3b)
http://highered.mcgraw-hill.com/sites/0072556781/student_view0/chapter31/animation_quiz_1.html
Complement system(animation)
Laboratory tests for complement assesment
Quantification of compoments (C3, C4, MBL - RID, nephelometry)
- concentration: g/L (mg/ml)
Functional testsfor classical and alternative pathway of activation
10.____9.____8.____7.____5._____4._____3._____2._____
C3a, C4a and C5aj.Osmotic lysis of microbes are mediated by10.
C3bi.Inflammatory reactions are induced by9.
MACh.Important opsonin is8.
C3 componentg.Proteins involved in early steps of classical pathway are
7.
IgM and IgG bound to antigenf.Components of alternative pathway are6.
C1, C4, C2e.Activators of classical pathway are 5.
classical, alternative and lectind.First component in lectin pathway is4.
factor B, factor D, properdinc.Central role in complement activation belongs to
3.
effector mechanism of innate and adaptive immunity
b.Complement activation pathways are2.
mannose binding lectin (MBL)a.Activation of complement system is1.
1._____ 6.____d g a f c e i jb h