title: IL-15 is required for sustained lymphopenia-driven proliferation and accumulation of CD8 T cells.
abstract: Naive T cells undergo slow homeostatic proliferation in response to T cell lymphopenia, which is also called lymphopenia-induced proliferation (LIP). IL-7 is critically required for this process, but previous studies suggested IL-15 was expendable for LIP of naive CD8 T cells. In contrast, we show that IL-15 is important for sustained CD8 T cell proliferation and accumulation in a lymphopenic setting, as revealed by truncated LIP in IL-15(-/-) hosts. At the same time, we find that IL-12 enhances LIP by acting directly on the CD8 T cells and independently of IL-15, suggesting distinct pathways by which cytokines can regulate homeostatic proliferation. Interestingly, the memory-phenotype CD8 T cell generated by LIP in IL-15(-/-) hosts are phenotypically distinct from the rare endogenous memory-phenotype cells found in IL-15(-/-) animals, suggesting these cells are generated by different means. These findings demonstrate that cytokine requirements for LIP change during the process itself, illustrating the need to identify factors that regulate successive stages of lymphopenia-driven proliferation.
authors.affiliation: Center for Immunology, Department of Laboratory Medicine and Pathology, University of Minnesota, 420 Delaware Street SE, Minneapolis, MN 55455, USA.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Sandau
authors.forename: Colleen J
authors.initials: CJ
authors.lastname: Winstead
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Jameson
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*; D002449:Cell Aggregation / Q000235:genetics / Q000276:immunology; D049109:Cell Proliferation; D007156:Immunologic Memory / Q000235:genetics; D016130:Immunophenotyping; D019409:Interleukin-15 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D008213:Lymphocyte Activation / Q000235:genetics / Q000276:immunology; D008231:Lymphopenia / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D016192:Resting Phase, Cell Cycle / Q000235:genetics / Q000276:immunology; D013997:Time Factors
chemical_list: D019409:Interleukin-15