The amplification loop of the complement pathways

PJ Lachmann - Advances in immunology, 2009 - Elsevier
The C3 amplification loop lies at the core of all the complement pathways, rather than the
alternative pathway alone. It is, in evolutionary terms, the oldest part of the complement
system and its antecedents can be seen in insects and in echinoderms. The amplification
loop is the balance between two competing cycles both acting on C3b: the C3 feedback
cycle which enhances amplification and the C3 breakdown cycle which downregulates it. It
is solely the balance between their rates of reaction on which amplification depends. The C3 …