CD19 function in early and late B cell development. II. CD19 facilitates the pro-B/pre-B transition

J Immunol. 2003 Dec 1;171(11):5921-30. doi: 10.4049/jimmunol.171.11.5921.

Abstract

Proliferative expansion of pro-B cells is an IL-7-dependent process that allows for the rearrangement of H chain genes and the expression of the pre-B cell receptor (pre-BCR). Further B cell differentiation is dependent upon signals elicited through the pre-BCR, which are thought to be responsible for allelic exclusion, induced L chain gene rearrangement, and continued proliferation. CD19 promotes the proliferation and survival of mature B cells, but its role in early B cell development is less well understood. Here we identify and characterize impairments in early B cell development in CD19(-/-) mice. Following sublethal irradiation, we found decreased numbers of autoreconstituted early B cells, which was first evident in the large cycling pre-B cell fraction. Reduced cell progression due to a defect in proliferation was made evident from cell cycle analysis and bromodeoxyuridine labeling of bone marrow cells from CD19(-/-) and wild-type mice. Studies of IL-7-dependent pre-B cell cultures derived from wild-type and CD19(-/-) mouse bone marrow suggested that CD19 has little affect on IL-7 signaling. By contrast, signaling through the pre-BCR was impaired in the absence of CD19, as demonstrated by reduced activation of Bruton's tyrosine kinase and extracellular signal-regulated kinase/mitogen-activated protein kinase. Thus, in addition to promoting mature B cell homeostasis and Ag-induced responses, the early onset of CD19 expression acts to enhance B cell generation.

Publication types

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

MeSH terms

  • Animals
  • Antigens, CD19 / genetics
  • Antigens, CD19 / physiology*
  • B-Lymphocyte Subsets / cytology*
  • B-Lymphocyte Subsets / immunology*
  • B-Lymphocyte Subsets / metabolism
  • Bone Marrow / immunology
  • Bone Marrow / radiation effects
  • Cell Differentiation / genetics
  • Cell Differentiation / immunology
  • Cell Division / genetics
  • Cell Division / immunology
  • Cells, Cultured
  • Crosses, Genetic
  • Down-Regulation / genetics
  • Down-Regulation / immunology
  • Hematopoietic Stem Cells / cytology*
  • Hematopoietic Stem Cells / immunology*
  • Hematopoietic Stem Cells / metabolism
  • Membrane Glycoproteins / biosynthesis*
  • Membrane Glycoproteins / physiology
  • Mice
  • Mice, Inbred BALB C
  • Mice, Knockout
  • Mice, Transgenic
  • Pre-B Cell Receptors
  • Radiation Chimera / immunology
  • Receptors, Antigen, B-Cell / biosynthesis*
  • Receptors, Antigen, B-Cell / physiology
  • Signal Transduction / genetics
  • Signal Transduction / immunology

Substances

  • Antigens, CD19
  • Membrane Glycoproteins
  • Pre-B Cell Receptors
  • Receptors, Antigen, B-Cell