Identification of the earliest B lineage stage in mouse bone marrow

Immunity. 1996 Dec;5(6):527-35. doi: 10.1016/s1074-7613(00)80268-x.


We have identified a very early stage of B lineage cells in the CD45R (B220)+CD24 (HSA) pre-pro-B fraction of mouse bone marrow delineated by expression of AA4.1, a molecule found on stem cells and early B lineage cells. These cells are B lineage precursors based on their capacity to generate B lineage cells rapidly in stromal-dependent culture and their expression of high levels of germline IgH transcripts in the absence of Rag-1/2. Half of these AA4.1+ precursors express low levels of CD4, characteristic of lymphoid progenitors, but few if any have up-regulated CD19, a molecule expressed very early in the B lineage. Furthermore, expression of genes encoding pre-B and B cell receptor components (mb-1, B29, and lambda 5) and transcription factors necessary for B lineage differentiation (BSAP, E12, E47, and Id) provide further support for designating these cells as the earliest B cell precursors.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antigens, Differentiation
  • B-Lymphocyte Subsets
  • B-Lymphocytes*
  • Bone Marrow / embryology*
  • Bone Marrow Cells
  • Cell Differentiation
  • Cell Fractionation
  • Cell Lineage
  • DNA-Binding Proteins*
  • Female
  • Gene Expression
  • Hematopoietic Stem Cells*
  • Homeodomain Proteins*
  • Immunoglobulin Isotypes / biosynthesis
  • Mice
  • Mice, Inbred BALB C
  • Phenotype
  • Protein Biosynthesis
  • Transcription Factors / biosynthesis
  • Transcription, Genetic


  • Antigens, Differentiation
  • DNA-Binding Proteins
  • Homeodomain Proteins
  • Immunoglobulin Isotypes
  • Rag2 protein, mouse
  • Transcription Factors
  • V(D)J recombination activating protein 2
  • RAG-1 protein