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Isolation of Tonsillar Mononuclear Cells to Study Ex Vivo Innate Immune Responses in a Human Mucosal Lymphoid Tissue
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Isolation of Tonsillar Mononuclear Cells to Study Ex Vivo Innate Immune Responses in a Human Mucosal Lymphoid Tissue

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CD5+ B cells with the features of subepithelial B cells found in human tonsils

Mariella Dono1, Vito Lelio Burgio, Monica Colombo

  • 1S.C. Oncologia Medica C, Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy.

European Journal of Immunology
|July 7, 2007
PubMed

Insights

Researchers identified a unique CD5+ B cell population in human tonsils. These cells exhibit distinct surface markers and functional properties, differing from typical CD5+ B cells and sharing characteristics with marginal zone B cells.

Area of Science:

  • Immunology
  • B cell biology

Background:

  • Human tonsils contain diverse B cell populations.
  • CD5+ B cells are typically associated with the follicular mantle, distinct from marginal zone (MZ) B cells.

Purpose of the Study:

  • To characterize a novel CD5+ B cell subset found in human tonsils.
  • To compare this subset with known tonsillar B cell populations and splenic MZ B cells.

Main Methods:

  • Isolation and analysis of CD5+ B cells from human tonsils.
  • Flow cytometry for surface marker expression (CD5, CD23, IgM, IgD, CD27).
  • In vitro functional assays using T cell-independent type-2 antigens.
  • Analysis of immunoglobulin variable heavy (Ig VH) gene sequences.

Main Results:

  • A CD5+ B cell subset was identified with a CD23-, IgMhigh, IgDlow phenotype, expressing activation markers.
  • These cells were located in subepithelial (SE) areas, analogous to splenic MZ.
  • The cells responded to T cell-independent type-2 antigens in vitro.
  • Most cells used unmutated Ig VH genes, but mutated sequences were also found, particularly in CD27+ enriched populations.
  • Evidence of in situ expansion was observed through repeated VDJ gene sequences.

Conclusions:

  • This study describes a distinct CD5+ B cell population in tonsils with characteristics of MZ B cells.
  • These cells differ significantly from the majority of tonsillar CD5+ B cells.
  • The findings contribute to understanding B cell subset origins and the relationship between MZ and B1 cells.

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