Characterization of human FCRL4-positive B cells

PLoS One. 2017 Jun 21;12(6):e0179793. doi: 10.1371/journal.pone.0179793. eCollection 2017.

Abstract

FCRL4 is an immunoregulatory receptor that belongs to the Fc receptor-like (FCRL) family. In healthy individuals, FCRL4 is specifically expressed by memory B cells (MBCs) localized in sub-epithelial regions of lymphoid tissues. Expansion of FCRL4+ B cells has been observed in blood and other tissues in various infectious and autoimmune disorders. Currently, the mechanisms involved in pathological FCRL4+ B cell generation are actively studied, but they remain elusive. As in vivo FCRL4+ cells are difficult to access and to isolate, here we developed a culture system to generate in vitro FCRL4+ B cells from purified MBCs upon stimulation with soluble CD40 ligand and/or CpG DNA to mimic T-cell dependent and/or T-cell independent activation, respectively. After 4 days of stimulation, FCRL4+ B cells represented 17% of all generated cells. Transcriptomic and phenotypic analyses of in vitro generated FCRL4+ cells demonstrated that they were closely related to FCRL4+ tonsillar MBCs. They strongly expressed inhibitory receptor genes, as observed in exhausted FCRL4+ MBCs from blood samples of HIV-infected individuals with high viremia. In agreement, cell cycle genes were significantly downregulated and the number of cell divisions was two-fold lower in in vitro generated FCRL4+ than FCRL4- cells. Finally, due to their reduced proliferation and differentiation potential, FCRL4+ cells were less prone to differentiate into plasma cells, differently from FCRL4- cells. Our in vitro model could be of major interest for studying the biology of normal and pathological FCRL4+ cells.

MeSH terms

  • ADP-ribosyl Cyclase 1 / metabolism
  • Antigens, CD20 / metabolism
  • B-Lymphocytes / cytology
  • B-Lymphocytes / metabolism*
  • Cell Differentiation
  • Cell Proliferation
  • Cells, Cultured
  • Cytokines / pharmacology
  • Down-Regulation
  • HIV Infections / immunology
  • HIV Infections / pathology
  • HIV Infections / virology
  • Humans
  • Immunophenotyping
  • Phenotype
  • Receptors, Fc / genetics
  • Receptors, Fc / metabolism*
  • Transcriptome

Substances

  • Antigens, CD20
  • Cytokines
  • FCRL4 protein, human
  • Receptors, Fc
  • ADP-ribosyl Cyclase 1

Grants and funding

This work was supported by Institut National du Cancer (2012-109/087437 and PLBIO15-256), Conseil Régional Languedoc Roussillon (R14026FF), Fondation de France (201400047510), Institut Thématique Multi-organismes Cancer (MM&TT) and SIRIC Montpellier (INCa-DGOS-Inserm 6045).