A Highly Effective Immune System Predating Adaptive Immunity
Stepwise diversification. The coeloma cavities of the deuterostome sea urchins (Strongylocentrotus purpuratus) mobilize monocyte-like cells, which respond to bacterial endotoxins. The diversity of the response of sea urchin coelomocytes to lipopolysaccharides was unexpectedly high: 81 full length cDNAs contained 67 unique nucleotide sequences (the 185/333 family) encoding 64 different proteins. Complement C3 was expressed, too.