Interactions between endotoxic lipopolysaccharides and the complement system in the sera of lower vertebrates.

SummaryEndotoxic lipopolysaccharides (LPS) have potent ability to consume complement (C) components and generate biologically active peptides from the C system in normal mammalian serum. The present investigation shows that LPS derived from Escherichia coli has potent ability to consume hemolytic C in all vertebrate species in which C activity is detectable, including species as low phylogenetically as representative Chon-drichthyes (horned shark, nurse shark), Os-teichthyes (paddlensh, carp), Amphibia (bull frog, marine frog), and Reptilia (cobra, turtle). Hence, the consumption of C components in response to this ubiquitous bacterial product is a characteristic of vertebrate serum virtually throughout vertebrate evolution.