title: Alternative adaptive immunity in jawless vertebrates.
abstract: Jawless vertebrates use variable lymphocyte receptors (VLRs) that are generated by RAG-independent combinatorial assembly of leucine-rich repeat cassettes for Ag recognition, instead of the Ig-based Ag receptors used by jawed vertebrates. The VLR genes encode for crescent-shaped proteins that use variable beta-strands and a C-terminal loop to bind to Ags rather than the six CDR loops used by BCRs and TCRs. VLR mAbs have been isolated recently, which enabled the structure of VLR-Ag complexes to be defined. The jawless vertebrate adaptive immune system has many similarities to the Ig-based system of jawed vertebrates, including the compartmentalized development of B-like and T-like lymphocyte lineages that proliferate and differentiate into VLR-secreting plasmacytes and proinflammatory cytokine-producing cells in response to Ags. The definition of common features of the VLR-based and Ig-based systems offers fresh insight into the evolution of adaptive immunity.
authors.affiliation: Department of Pathology and Laboratory Medicine, Emory Vaccine Center, Emory University School of Medicine, Atlanta, GA 30322, USA. brantley.herrin@emory.edu
authors.forename: Brantley R
authors.initials: BR
authors.lastname: Herrin
authors.forename: Max D
authors.initials: MD
authors.lastname: Cooper
mesh_terms: D056704:Adaptive Immunity / Q000235:genetics; D000818:Animals; D019143:Evolution, Molecular; D006196:Hagfishes / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D007135:Immunoglobulin Variable Region / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D007568:Jaw / Q000033:anatomy & histology; D048428:Petromyzon / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D011946:Receptors, Antigen / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: D007135:Immunoglobulin Variable Region; D011946:Receptors, Antigen