Complement Systems Flashcards
What is the Complement Sysytem?
Group of about 30 serum proteins that interact in a cascade to kill bacteria.
Are complement protein always present in the serum?
What activates them?
YES
Infection
Where are complement proteins made?
What makes them?
In the liver under normal conditions
By Myeloid cells (during inflammation response)
Three Pathways of Complement Activation….
- Classical pathway
- Alternative pathway
- Lectin pathway
Pathways of Complement activation that are part of the innate immune system….
- Alternative pathway
- Pathogen surface makes environment more likely to complement activation. - Lectin pathway
- Mannose-biding protein binds pathogen surface
Pathways of Complement activation that are part of the acquired immune system
- Classical Pathway
- Antibody binds to SPECIFIC antigen on pathogen surface.
When is each pathway of the complement system initiated? (Not just not just inflammatory response)
When a complement component in serum binds to the surface of a pathogen.
**Initial steps are diff. for each pathway
Sequential activation….
A series of enzymes activate other complement proteins in SEQUENCE
What happens during each step of sequential activation?
“Domino Effect”
An active complement enzyme cleaves (proteolyses) & activates the next enzyme in the pathway.
Amplification…
Like At&t….We want more, we want more!!
Each complement enzyme activates MULTIPLE molecules of the next complement protein in the cascade.
Regulation….
The Party Poopers….
Complement activity is tightly regulated to prevent uncontrolled or inappropriate activation.
Multiple regulatory proteins LIMIT DAMAGE to pathogens.
What brings the 3 complement activation pathways 2gether?
Cleavage of C3 complement —-> C3B intermediate
What is the abbreviation for complement proteins?
“CX”
X= 1-9
What is used to designate complement fragments?
A lowercase letter usually a or b
C3 9 = …….
C3a+ C3b
