Unlike mammalian species, several cold-blooded species have been shown
to possess multiple forms of complement components. The multiple form
s of C3 characterized in several fish species can bind with different
specificities to various complement-activating surfaces. Here, Oriol S
unyer, Ioannis Zarkadis and John Lambris explore the possible advantag
es conferred by having multiple forms of individual complement protein
s in a single organism.