title: Il-12 enhances CD8 T cell homeostatic expansion.
abstract: The size of the T lymphocyte pool is maintained by regulation of T cell production, proliferation, and survival. Under the pressure of a T lymphopenic environment, mature naive T cells begin to proliferate in the absence of Ag, a process called homeostatic expansion. Homeostatic expansion involves TCR recognition of self peptide/MHC ligands, but less is known about the soluble factors that regulate this process. Here we show that IL-12 dramatically enhanced the homeostatic proliferation of CD8 T cells. In contrast, IL-2 had no beneficial effect on homeostatic expansion and, in fact, inhibited T cell expansion induced by IL-12. Using gene-targeted mice, we showed that IL-12 acted directly on the T cells to enhance homeostatic expansion, but that IL-12 cannot override the requirement for TCR interaction with self peptide/MHC ligands in homeostatic expansion. These data indicate that inflammatory cytokines may modulate T cell homeostasis after lymphopenia and have implications for regulation of the T cell repertoire and autoimmunity.
authors: Department of Laboratory Medicine and Pathology, University of Minnesota Center for Immunology, Minneapolis, MN 55455, USA.
authors: W C
authors: WC
authors: Kieper
authors: M
authors: M
authors: Prlic
authors: C S
authors: CS
authors: Schmidt
authors: M F
authors: MF
authors: Mescher
authors: S C
authors: SC
authors: Jameson
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000502:physiology*; D019264:Adoptive Transfer; D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism / Q000637:transplantation; D002455:Cell Division / Q000235:genetics / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000096:biosynthesis / Q000235:genetics; D006706:Homeostasis / Q000235:genetics / Q000276:immunology*; D016130:Immunophenotyping; D007274:Injections, Intraperitoneal; D018664:Interleukin-12 / Q000008:administration & dosage / Q000502:physiology*; D007399:Interphase / Q000235:genetics / Q000276:immunology; D008213:Lymphocyte Activation / Q000235:genetics; D018655:Lymphocyte Count; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D015395:Histocompatibility Antigens Class I; D011948:Receptors, Antigen, T-Cell; D018664:Interleukin-12