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X Complement
A group of serum proteins that activates
each other in an orderly fashion to generate
biologically active molecules.
Like enzymes, opsonins (Candy Coat)
Anaphalatoxins (Histamine like) and
Chemotaxins (Draw cells to the site)
http://users.rcn.com/jkimball.
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mplement.html
DISCOVERY

In 1894, Pfeiffer discovered that
Vibrio cholerae were lysed in vitro by
the addition of guinea pig anti-cholera
serum.

Heating the serum to 56 C for 30 min
abolished this activity

, but did not abolish the biological
activity of antibodies as passive
resistance could be transferred.

He also discovered that the lytic
activity could be re-established with
the addition of fresh serum to the
heat treated serum.

From this he concluded that an
additional component (in addition to
Ab) was present in the serum. He
called this substance complement.
JULES BURDET WAS
AWARDED THE NOBEL
PRIZE IN MEDICINE IN 1919
FOR HIS DEMONSTRATION
OF THE ACTIVITY OF
COMPLEMENT
A. Pathways


1. Classical – Complement binds with
Ag-Ab complexes – especially IgM’s;
IgG’s fix complement to a lesser
extent. This is the usual way
complement is activated.
2. Alternate - cell walls of some (very
few) bacteria and yeast in
combination with several serum
factors
B. BIOLOGICAL ACTIVITY




1. lyse membranes
2. degranulate mast cells anaphylatoxins
3. chemotaxins- attract phagocytic cells
(move from low conc. to high conc.)


4. immune adherence - Ag w/ Ab and
complement bind to blood vessels
5. opsonization - coating antigen to
render the cell more attractive to
phagocytic cells