Historecognition and Immunocompetence in Selected Marine Invertebrates

Abstract

All marine invertebrates must deal with pathogens, parasites and transformed cells. Sessile marine invertebrates must also meet the additional challenge of coming into contact with allogeneic and xenogeneic tissues. All invertebrate phyla examined demonstrate some degree of specific nonself reactions. Some sponges, scleractinian corals, gorgonians, echinoderms, and tunicates have demonstrated the existence of an alloimmune system by fulfilling the three functional criteria of: (1) cytotoxic reactions; (2) specificity; and (3) an inducible memory. Marine invertebrate immunologic memory is relatively short term, up to six months, but that could be significant, at least within the parameters of the animal’s life style. Tissue fusions require a positive recognition of self and the separate systems for allogeneic or xenogeneic tissue rejection require a positive recognition of nonself. Medawar’s concept of the “uniqueness of the individual” seems to be widely applicable but other systems/situations may occur. Hildemann’s proposal that cell mediated immunity arose early in metazoan evolution and Ig mediated responses appeared early in the vertebrates seems to be serving as a good working hypothesis. There are a number of other histoincompatibility systems in sessile marine invertebrates, e.g., sea anemone aggression, that share features with the alloimmune responses and could perhaps utilize related recognition molecules.