title: Identification of very early lymphoid precursors in bone marrow and their regulation by estrogen.
abstract: Estrogen is a negative regulator of lymphopoiesis and provides an experimental tool for probing relationships between lymphocyte precursors and stem cells. We found that expression of lymphocyte-associated genes and immunoglobulin (Ig) gene rearrangement occurred before CD45R acquisition. Lymphoid-restricted progenitors that were Lin(-)IL-7R alpha(+)c-kit(lo)TdT(+) (lineage marker(-), interleukin receptor 7 alpha(+), c-kit(lo) and terminal deoxynucleotidyl transferase(+)) were selectively depleted in estrogen-treated mice; within a less differentiated Lin-c-kit(hi) fraction, functional precursors of B and T, but not myeloid, cells were also selectively depleted. TdT and an Ig heavy chain transgene were detected within a hormone-regulated Lin(-)c-kit(hi)Sca-1(+)CD27(+)Flk-2(+)IL-7R alpha(-) subset of this multipotential progenitor population. Identification of these extremely early lymphoid precursors should facilitate investigation of the molecular mechanisms that control lineage-fate decisions in hematopoiesis.
authors.affiliation: Immunobiology and Cancer Program, Oklahoma Medical Research Foundation, 825 N.E. 13th Street, Oklahoma City, OK 73104, USA.
authors.forename: K L
authors.initials: KL
authors.lastname: Medina
authors.forename: K P
authors.initials: KP
authors.lastname: Garrett
authors.forename: L F
authors.initials: LF
authors.lastname: Thompson
authors.forename: M I
authors.initials: MI
authors.lastname: Rossi
authors.forename: K J
authors.initials: KJ
authors.lastname: Payne
authors.forename: P W
authors.initials: PW
authors.lastname: Kincade
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000502:physiology*; D019070:Cell Lineage / Q000276:immunology; D004967:Estrogens / Q000502:physiology*; D006410:Hematopoiesis / Q000502:physiology*; D008214:Lymphocytes / Q000166:cytology* / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL
chemical_list: D004967:Estrogens