Regulated expression of BAFF-binding receptors during human B cell differentiation

J Immunol. 2007 Dec 1;179(11):7276-86. doi: 10.4049/jimmunol.179.11.7276.

Abstract

BAFF plays a central role in B-lineage cell biology; however, the regulation of BAFF-binding receptor (BBR) expression during B cell activation and differentiation is not completely understood. In this study, we provide a comprehensive ex vivo analysis of BBRs in human B-lineage cells at various stages of maturation, as well as describe the events that drive and regulate receptor expression. Our data reveal that B-lineage cells ranging from naive to plasma cells (PCs), excluding bone marrow PCs, express BAFF-R uniformly. In contrast, only tonsillar memory B cells (MB) and PCs, from both tonsil and bone marrow tissues, express BCMA. Furthermore, we show that TACI is expressed by MB cells and PCs, as well as a subpopulation of activated CD27(neg) B cells. In this regard, we demonstrate that TACI is inducible early upon B cell activation and this is independent of B cell turnover. In addition, we found that TACI expression requires activation of the ERK1/2 pathway, since its expression was blocked by ERK1/2-specific inhibitors. Expression of BAFF-R and B cell maturation Ag (BCMA) is also highly regulated and we demonstrate that BCMA expression is only acquired in MB cells and in a manner accompanied by loss of BAFF-R expression. This inverse expression coincides with MB cell differentiation into Ig-secreting cells (ISC), since blocking differentiation inhibited both induction of BCMA expression and loss of BAFF-R. Collectively, our data suggest that the BBR profile may serve as a footprint of the activation history and stage of differentiation of normal human B cells.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • B-Cell Activation Factor Receptor / biosynthesis*
  • B-Cell Maturation Antigen / biosynthesis
  • B-Lymphocytes / cytology
  • B-Lymphocytes / immunology*
  • Butadienes / pharmacology
  • Cell Differentiation / immunology
  • Flavonoids / pharmacology
  • Humans
  • Mitogen-Activated Protein Kinase 1 / immunology
  • Mitogen-Activated Protein Kinase 3 / immunology
  • Nitriles / pharmacology
  • Signal Transduction / immunology
  • Transmembrane Activator and CAML Interactor Protein / antagonists & inhibitors
  • Transmembrane Activator and CAML Interactor Protein / biosynthesis

Substances

  • B-Cell Activation Factor Receptor
  • B-Cell Maturation Antigen
  • Butadienes
  • Flavonoids
  • Nitriles
  • TNFRSF13B protein, human
  • TNFRSF13C protein, human
  • Transmembrane Activator and CAML Interactor Protein
  • U 0126
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one