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- Title
Evolutionary implications of a third lymphocyte lineage in lampreys.
- Authors
Hirano, Masayuki; Guo, Peng; McCurley, Nathanael; Schorpp, Michael; Das, Sabyasachi; Boehm, Thomas; Cooper, Max D.
- Abstract
Jawed vertebrates (gnathostomes) and jawless vertebrates (cyclostomes) have different adaptive immune systems. Gnathostomes use T- and B-cell antigen receptors belonging to the immunoglobulin superfamily. Cyclostomes, the lampreys and hagfish, instead use leucine-rich repeat proteins to construct variable lymphocyte receptors (VLRs), two types of which, VLRA and VLRB, are reciprocally expressed by lymphocytes resembling gnathostome T and B cells. Here we define another lineage of T-cell-like lymphocytes that express the recently identified VLRC receptors. Both VLRC+ and VLRA+ lymphocytes express orthologues of genes that gnathostome γδ and αβ T cells use for their differentiation, undergo VLRC and VLRA assembly and repertoire diversification in the 'thymoid' gill region, and express their VLRs solely as cell-surface proteins. Our findings suggest that the genetic programmes for two primordial T-cell lineages and a prototypic B-cell lineage were already present in the last common vertebrate ancestor approximately 500 million years ago. We propose that functional specialization of distinct T-cell-like lineages was an ancient feature of a primordial immune system.
- Subjects
VERTEBRATES; AGNATHA; GENES; LYMPHOCYTES; IMMUNITY; CELL membranes; PROTEINS
- Publication
Nature, 2013, Vol 501, Issue 7467, p435
- ISSN
0028-0836
- Publication type
Article
- DOI
10.1038/nature12467