title: Lamprey variable lymphocyte receptors mediate complement-dependent cytotoxicity.
abstract: An alternative adaptive-immune system is present in the most basal vertebrates--lampreys and hagfish--the only surviving jawless vertebrates. These eel-like fish use leucine-rich repeat-based receptors for Ag recognition instead of the Ig-based receptors used in jawed vertebrates. We report that in Japanese lamprey (Lampetra japonica), variable lymphocyte receptor (VLR)B interacts with C1q and C3 proteins to mediate complement-dependent cytotoxicity for bacteria and tumor cells. The immune-based lysis involves deposition of VLRB and C1q-like protein complex on the surface of target cells, activation of C3, and ultimate disruption of cell wall integrity. The demonstration of functional interaction between VLRB and complement components in lamprey provides evidence for the emergence of cooperative innate and adaptive-immune responses at a pivotal point in vertebrate evolution, before or in parallel with the evolution of Ig-based Abs and the classical complement-activation pathway.
authors.affiliation: College of Life Science, Liaoning Normal University, Dalian, Liaoning 116029, China.
authors.forename: Fenfang
authors.initials: F
authors.lastname: Wu
authors.forename: Liyong
authors.initials: L
authors.lastname: Chen
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.forename: Huaying
authors.initials: H
authors.lastname: Wang
authors.forename: Peng
authors.initials: P
authors.lastname: Su
authors.forename: Yinglun
authors.initials: Y
authors.lastname: Han
authors.forename: Bo
authors.initials: B
authors.lastname: Feng
authors.forename: Xu
authors.initials: X
authors.lastname: Qiao
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.forename: Ning
authors.initials: N
authors.lastname: Ma
authors.forename: Huijie
authors.initials: H
authors.lastname: Liu
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zheng
authors.forename: Qingwei
authors.initials: Q
authors.lastname: Li
mesh_terms: D056704:Adaptive Immunity; D000372:Agglutination Tests; D000818:Animals; D001407:Bacillus; D045744:Cell Line, Tumor; D003167:Complement Activation; D015922:Complement C1q / Q000276:immunology; D003176:Complement C3 / Q000276:immunology; D003165:Complement System Proteins / Q000276:immunology*; D004926:Escherichia coli; D006367:HeLa Cells; D006801:Humans; D007114:Immunization; D007798:Lampreys / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D020102:Mycobacterium smegmatis; D011971:Receptors, Immunologic / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology; D013211:Staphylococcus aureus
chemical_list: D003176:Complement C3; D011971:Receptors, Immunologic; D011994:Recombinant Proteins; D015922:Complement C1q; D003165:Complement System Proteins