Evolution of Alternative Adaptive Immune Systems in Vertebrates.
Annu Rev Immunol
; 36: 19-42, 2018 04 26.
Article
em En
| MEDLINE
| ID: mdl-29144837
Adaptive immunity in jawless fishes is based on antigen recognition by three types of variable lymphocyte receptors (VLRs) composed of variable leucine-rich repeats, which are differentially expressed by two T-like lymphocyte lineages and one B-like lymphocyte lineage. The T-like cells express either VLRAs or VLRCs of yet undefined antigen specificity, whereas the VLRB antibodies secreted by B-like cells bind proteinaceous and carbohydrate antigens. The incomplete VLR germline genes are assembled into functional units by a gene conversion-like mechanism that employs flanking variable leucine-rich repeat sequences as templates in association with lineage-specific expression of cytidine deaminases. B-like cells develop in the hematopoietic typhlosole and kidneys, whereas T-like cells develop in the thymoid, a thymus-equivalent region at the gill fold tips. Thus, the dichotomy between T-like and B-like cells and the presence of dedicated lymphopoietic tissues emerge as ancestral vertebrate features, whereas the somatic diversification of structurally distinct antigen receptor genes evolved independently in jawless and jawed vertebrates.
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01-internacional
Base de dados:
MEDLINE
Assunto principal:
Vertebrados
/
Evolução Biológica
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Imunidade Adaptativa
Limite:
Animals
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Humans
Idioma:
En
Revista:
Annu Rev Immunol
Ano de publicação:
2018
Tipo de documento:
Article