Workshop 33 - Phylogenetic Aspects of Immunity

Abstract

This chapter presents an overview of the workshop highlighting phylogenetic aspects of immunity. A broad range of current research in immunologic phylogeny was considered by some 65 participants under six major headings. The chapter highlights that the long-held assumption that invertebrates in general completely lack specific, vertebrate-type immunocompetence has been disproved by various investigators in diverse phylums. Indeed, the essential origins of immunologic reactivity may soon be discerned among invertebrates. Both allograft and xenograft rejection, usually chronic but some times more rapid, are already demonstrable in coelenterates, although involvement of an immunological system at this low level of phylogeny is questionable. Specific transplantation immunity accompanied by at least short-term memory has been repeatedly found in annelid worms. This capacity is associated with development of cellular immunity inherent in a population of coelomocytes which includes both macrophages and small lymphocyte-type cells. The chapter also highlights that hagfish and lampreys, though most primitive among vertebrates, appear to be as highly evolved as other fishes below the teleost level in essential immunological capacities. They consistently reject skin allografts with concomitant immunological memory and produce IgM-type antibodies to both soluble and particulate antigens.