Purification and functional assessment of C3a, C4a and C5a of the common carp (Cyprinus carpio) complement.

Promotion of inflammatory response is an important role of the complement system, but this kind of function is poorly documented for the lower vertebrates. Here we report chemotactic activity of purified anaphylactic fragments derived from the complement components C3, C4 and C5 of the common carp. The purified anaphylatoxins are two C5a-desArg peptides derived from the C5-I isotype, an intact form and a desArg form of C4a from C4-2 isotype, and an intact form and a desArg form of C3a from C3-H1 isoform. These were identified by N-terminal sequencing, mass spectrometry, and peptide mass fingerprinting. In the chemotaxis assay using carp kidney neutrophils, the two C5a-desArg fragments, which are probably allotypic variants, showed a potent chemotactic activity at 0.5-1 nM, whereas C3a or C4a showed no significant activity. The results suggest that C3a, C4a and C5a of bony fish have functionally diverged to the state similar to their mammalian homologs.