title: Increased generation of CD8 single positive cells in SOCS1-deficient thymus does not proportionately increase their export.
abstract: Mice lacking suppressor of cytokine signaling 1 (SOCS1) accumulate CD8(+) T lymphocytes in the thymus and in the periphery. Whereas IL-7 and IL-15 promote the generation of CD8 single positive (SP) thymocytes, IL-15 drives the expansion of CD8 T cells in the periphery. Here, we investigated whether increased production of CD8 SP thymocytes is accompanied by their increased export in SOCS1-deficient mice. In vivo labeling with bromodeoxyuridine showed increased cycling of CD8 SP thymocytes in SOCS1-deficient mice. However, SOCS1-deficient thymi contained increased proportion of CD24(lo)CD69(lo) SP thymocytes as well as increased expression of Qa-2 in both CD4 and CD8 SP compartments. Analysis of recent thymic emigrants (RTE) following intrathymic labeling with fluorescein isothiocyanate revealed less efficient export of CD8 RTEs from SOCS1-deficient thymi and comparable CD4:CD8 ratio among RTEs in SOCS1-null and control mice. These findings show that the rate of export of CD8 SP thymocytes is not proportional to their generation in SOCS1-deficient thymi and suggest the existence of homeostatic mechanisms controlling the egress of CD8 T cells.
authors.affiliation: Immunology Division, Department of Pediatrics, Faculty of Medicine and Health Sciences, University of Sherbrooke, 3001-12th Avenue North, Sherbrooke, QC J1H 5N4, Canada.
authors.forename: Subburaj
authors.initials: S
authors.lastname: Ilangumaran
authors.forename: Julien
authors.initials: J
authors.lastname: Gagnon
authors.forename: Chantal
authors.initials: C
authors.lastname: Leblanc
authors.forename: Philippe
authors.initials: P
authors.lastname: Poussier
authors.forename: Sheela
authors.initials: S
authors.lastname: Ramanathan
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology* / Q000276:immunology; D002454:Cell Differentiation; D002465:Cell Movement / Q000276:immunology*; D049109:Cell Proliferation; D006706:Homeostasis; D051379:Mice; D008810:Mice, Inbred C57BL; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins / Q000172:deficiency* / Q000235:genetics; D013950:Thymus Gland / Q000166:cytology* / Q000254:growth & development
chemical_list: C491590:Socs1 protein, mouse; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins