title: The evolution of nasal immune systems in vertebrates.
abstract: The olfactory organs of vertebrates are not only extraordinary chemosensory organs but also a powerful defense system against infection. Nasopharynx-associated lymphoid tissue (NALT) has been traditionally considered as the first line of defense against inhaled antigens in birds and mammals. Novel work in early vertebrates such as teleost fish has expanded our view of nasal immune systems, now recognized to fight both water-borne and air-borne pathogens reaching the olfactory epithelium. Like other mucosa-associated lymphoid tissues (MALT), NALT of birds and mammals is composed of organized lymphoid tissue (O-NALT) (i.e., tonsils) as well as a diffuse network of immune cells, known as diffuse NALT (D-NALT). In teleosts, only D-NALT is present and shares most of the canonical features of other teleost MALT. This review focuses on the evolution of NALT in vertebrates with an emphasis on the most recent findings in teleosts and lungfish. Whereas teleost are currently the most ancient group where NALT has been found, lungfish appear to be the earliest group to have evolved primitive O-NALT structures.
authors.affiliation: Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerque, NM, USA.
authors.forename: Ali
authors.initials: A
authors.lastname: Sepahi
authors.affiliation: Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerque, NM, USA. Electronic address: isalinas@unm.edu.
authors.forename: Irene
authors.initials: I
authors.lastname: Salinas
mesh_terms: D000818:Animals; D005075:Biological Evolution; D006801:Humans; D018928:Immunity, Mucosal / Q000276:immunology*; D008221:Lymphoid Tissue / Q000276:immunology; D009297:Nasal Mucosa / Q000276:immunology*; D014714:Vertebrates
keywords: Evolution; Mucosal immunity; NALT; Nasal immunity; Teleost fish; Vertebrates