title: The echinoid immune system and the phylogenetic occurrence of immune mechanisms in deuterostomes.
abstract: In this article, Courtney Smith and Eric Davidson reinterpret the published data on immune function in lower deuterostomes and primitive chordates. It leads them to a new model of immune system phylogeny in which MHC-directed T-cell responses are the last to evolve and are not derived from subchordate self-nonself recognition systems.
authors: Division of Biology, California Institute of Technology, Pasadena 91125.
authors: L C
authors: LC
authors: Smith
authors: E H
authors: EH
authors: Davidson
mesh_terms: D000818:Animals; D000917:Antibody Formation; D002816:Chordata, Nonvertebrate / Q000276:immunology*; D004447:Echinodermata / Q000276:immunology*; D005399:Fishes / Q000276:immunology; D007111:Immunity, Cellular; D008954:Models, Biological; D010802:Phylogeny; D012098:Reproduction / Q000276:immunology; D012617:Sea Urchins / Q000276:immunology; D013045:Species Specificity; D014184:Transplantation, Homologous / Q000276:immunology; D014561:Urochordata / Q000276:immunology*