COMPLEMENT SYSTEM

immunoserology

COMPLEMENT SYSTEM 

Complement system is a proteins in blood that helps in immune system to fight infections 

That can destroy microbes 

Classical

Alternate

Lectin

3 pathways of complement system

Classical Pathway

• It is triggered when antibodies (IgM or IgG) bind to invader 

Classical Pathway

• It uses C1 complex (C1q+C1r+C1s) to start

Alternative Pathway 

• It is trigger by pathogens surfaces and not by antibodies

• It acts fast 

Lectin Pathway

Triggered by mannose a sugar in microbes is recognized by MBL or Mannose Binding Lectin

Mannose binding lectin

is like a "sensor" that helps your body find and fight off infections by recognizing specific patterns on the surface of harmful microbes specifically itsmannose or sugar part

COMPLEMENT SYSTEM

Complement is a group of 30+ proteins but the core are C1 to C9 so it means it has 9 components and it is activated one by one (cascade) 

C1

Also called recognition unit that starts the reaction when they see antibody on invader or germ

C1q, C1r and C1s

3 parts of C1

C1q

binds to antibodies what part of C1

C1r

activates the next step what part of C1?

C1s

continues the chain reaction WHAT part of C1?

calcium

C1 proteins are held by ____together

CH2 domain of IgG

C1q, C1r and C1s found on?

C4, C2 and C3 

Activation units?

C4, C2 and C3 

These are early responders in cascade 

Their job is to amplify the signal and prepare for attack

C3a

C3 that causes inflammation

C3b

acts as opsonin that tags invaders so WBC can eat them

Membrane attack complex or MAC 

Which is the Final attack stage 

Where system creates a hole in the enemy cell to make it burst

Membrane attack complex or MAC 

C5-C9 are?

C5, C6 and C7 

Called membrane attack units

They “pore-forming” structure on the pathogens membrane

C8 and C9 

Called final membrane attack units

They finish the job by creating giant hole in pathogens wall called cytolysis or cell death

Cytolysis or cell death

Primary Final product of Complement system

Cytolysis and Immuneresponse (Chemotaxins, opsonins and anaphylatoxin)

3 end result of complement activation

Chemotaxins, opsonins and anaphylatoxin

3 types of immuneresponse

Anaphylatoxins

C4a, C3a and C5a

what type of immune response?

Opsonization

C3b what type of immuneresposnse

Lytic pathway

 C5b, C6, C7, C8 and C9 what type of Immune response?

Classical Pathway 

• Most complete of all pathways because it uses all 9 components from C1-C9 then starts at C1

• Slower vs other pathway 

Classical Pathway

• Triggers or activated by antigen-Antibody complex 

• Highly specific 

 “A” and “B”

C6-C9 complements are not splitting thats why they don't have?

C1-INH, MCP, DAF, CR1 and C4-bp

regulator and inhibitor om complement in initial classical pathway

C1-INH

C1r and C1s blocking so that C1 will activated and cleave C4 and C2

C4-bp

• binds to C4 to prevent forming C3 convertase Classical pathway

DAF(Decay Accelerating factor)

•  disassemble C3 convertase 

MCP (Membrane cofactor protein)

• Destroy C3 and C4

CR1 or Complement receptor 1

•  removes C3 and C4 on surface