Cell aggregation: Properties of cell surface factors from five species of sponge

Aggregation factors isolated from the cell surface of five species of sponge are shown to be specific in their ability to enhance cell aggregation. Factors from Haliclona viridis, Haliclona variabilis, Tedania ignis, Homaxinella rudis , and Dysidea crawshayi each exhibit the species specific enhancing effect and have no such effect in heterospecific cell‐factor combinations. Radioactively labeled cell free supernatant materials are shown to bind selectively to homospecific cells suggesting that cells contain specific receptors for attachment of the aggregation mediating materials. Finally, in several heterospecific combinations there was an inhibition of cell aggregation. The inhibitory agent was separated from the enhancing factor chromatographically. After removal of the inhibitory substance, the enhancing factor was still active in promoting cell aggregation of the homospecific cells only.