Identification of a Novel Bone Marrow-Derived B-Cell Progenitor Population That Coexpresses B220 and Thy-1 and Is Highly Enriched for Abelson Leukemia Virus Targets

Abstract

A novel stage in early B-lymphocyte differentiation has been identified in normal mouse bone marrow cells. Earlier work had demonstrated that bone marrow cells characterized by low levels of Thy-1 and lack of a panel of lineage markers (Thy-1^lo Lin⁻ cells) were highly enriched for pluripotent hematopoietic stem cells. In this paper, we present evidence that another bone marrow population, which expressed low levels of Thy-1 and coexpressed B220, a B-lineage-specific form of the leukocyte common antigen, contained early and potent precursors for B lymphocytes upon in vivo transfer to irradiated hosts. These Thy-1^lo B220⁺ cells, comprising 1 to 2% of bone marrow cells, were enriched for large cells in the mitotic cycle; the population lacked significant pluripotent hematopoietic stem cell activity and myeloid-erythroid progenitors. Most strikingly, Thy-1^lo B220⁺ cells represented a highly enriched population of bone marrow cells that could be targets of Abelson murine leukemia virus transformation. We propose that Thy-1^lo B220⁺ bone marrow cells represent the earliest stage of committed lymphocyte progenitors, intermediate in differentiation between Thy-1^lo Lin⁻ pluripotent stem cells and, in the B lineage, Thy-1⁻ B220⁺ pre-B cells.

View retraction statement:

Identification of a Novel Bone Marrow-Derived B-Cell Progenitor Population That Coexpresses B220 and Thy-1 and Is Highly Enriched for Abelson Leukemia Virus Targets