Specific immune response in the sea star Asterias rubens: production of "antibody-like" factors.

Axial organ cells from the sea star (Asterias rubens) inoculated 7 days before with TNP- or FITC-haptenated PAA beads and subsequently stimulated in vitro with the same antigen, produced and released a specific, soluble "antibody-like" substance that induced lysis of haptenated sheep erythrocytes. Fresh normal rabbit or guinea pig serum was essential for the lysis, suggesting the participation of complement components. The factor was produced by the total population of axial organ cells but not by nylon-wool adherent (B-like) or nonadherent (T-like) cells. These results provide further evidence of the existence, in the sea star, of a primitive immune system with characteristics reminiscent of the immune system of vertebrates.