The peptide ligands mediating positive selection in the thymus control T cell survival and homeostatic proliferation in the periphery.
Positive selection to self-MHC/peptide complexes has long been viewed as a device for skewing the T cell repertoire toward recognition of foreign peptides presented by self-MHC molecules. Here, we provide evidence for an alternative possibility, namely, that the self-peptides controlling positive selection in the thymus serve to maintain the longevity of mature T cells in the periphery. Surprisingly, when total T cell numbers are reduced, these self-ligands become overtly stimulatory and cause naive T cells to proliferate and undergo homeostatic expansion.
Ernst
B
B
Department of Immunology, IMM26, The Scripps Research Institute, La Jolla, California 92037, USA.
Lee
D S
DS
Chang
J M
JM
Sprent
J
J
Surh
C D
CD
D000818:Animals; D002470:Cell Survival; D000949:Histocompatibility Antigens Class II / Q000502:physiology; D006706:Homeostasis; D008213:Lymphocyte Activation; D051379:Mice; D008822:Mice, Transgenic; D010455:Peptides / Q000502:physiology*; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D013601:T-Lymphocytes / Q000502:physiology*; D013950:Thymus Gland / Q000502:physiology*
D000949:Histocompatibility Antigens Class II; D010455:Peptides; D011948:Receptors, Antigen, T-Cell