The Complement System (activating antibodies and beyond) Flashcards
what did richard friedrich johannes pfeiffer work with?
Working with Cholera bacilli
what did richard friedrich johannes pfeiffer note?
noted that guinea pig
anticholera serum lysed cells
richard friedrich johannes pfeiffer heated …
… anti serum at 56 deg C for 30 mins negated this acitvity
addition of fresh serum from control guinea pig restored…
… activity
richard friedrich johannes pfeiffer experiment conclusion?
Antibodies to Cholera, plus a heat-labile component present in the ‘antisera’ and ‘normal’ serum were required for lysis
Later Ehrich classified this
component as
Complement
What is Complement?
A group of serum proteins that act in a coordinated manner to exert their biological (immune) effect
Serum concentration of Complement DOES…
… NOT increase after immunisation
the complement system is a […] process between components of different pathways
the complement system is a DYNAMIC process between components of different pathways
how do complement proteins work?
- complement proteins insert themselves into the membrane of pathogens, creating a pore.
- water and ions enter the cell
- cell swells and lyses
what does the classical pathway require?
Requires antigen/antibody complexes for initiation
(immunoglobulins are potent activators of
Complement; Ig Gand IgM)
the alternative pathway is antibody …
independent.
in the alternative pathway, the pathogen surface provides a…
biochemical environment conducive with Complement initiation
what happens in the lectin pathway?
Mannose binding lectin binds to pathogen surface promotes initiation process
What does the classical pathway involve
Involves antibody (or c-reactive protein) binding to specific epitope on
antigen (pathogen)surface
The classical pathway involves the orderly activation of?
Orderly activation of nine major protein components (C1– C9)
some components in the classical pathway cascade are…
… enzymes
Amplification and activation of large amounts of complement from a small signal is…
… possible
the classical pathway is highly…
… regulated; each step is highly regulated
when does the classical pathway culminate?
Culminates in the C9 polymerisation around
the C5b678 complex -> membrane attack complex (perforin-like structure in pathogen
cell membrane)
C1 split into its 3 compoments…
C1q - 400 kDa
C1r - 95 kDa
C1s - 85 kDa
C1r and C1s are a…
… heterodimer
what kind of activity does C1s have?
C1s has esterolytic and
proteolytic activity that acts on the next component in the cascade = C4