Role of self-major histocompatibility complex/peptide ligands in selection and maintenance of a diverse T cell repertoire.
Positive selection has long been thought to be a devise for producing a repertoire of T cells that can efficiently recognize foreign peptides in the context of self-major histocompatibility complex (MHC) molecules. However, in the light of recent evidence that long-term survival of mature T cells requires continuous contact with self-MHC molecules, the possibility for an additional role for positive selection has emerged: to generate a repertoire of T cells that can be maintained in the periphery through contact with self-MHC/peptide ligands. In support of this idea, our recent work suggests that positive selection is highly peptide specific and, more important, that mature T cells require extrathymic contact with the same MHC/peptide ligands that initially induced positive selection in the thymus in order for prolonged survival and to undergo homeostatic proliferation in response to T cell deficiency.
Surh
C D
CD
Department of Immunology, The Scripps Research Institute, La Jolla, CA 92037, USA. csurh@scripps.edu
Ernst
B
B
Lee
D S
DS
Dummer
W
W
LeRoy
E
E
D000818:Animals; D002454:Cell Differentiation / Q000276:immunology; D006801:Humans; D008024:Ligands; D008285:Major Histocompatibility Complex / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
D008024:Ligands; D011948:Receptors, Antigen, T-Cell