B-1 B cell progenitors transiently and partially express keratin 5 during differentiation in bone marrow

J Dermatol Sci. 2016 Mar;81(3):173-81. doi: 10.1016/j.jdermsci.2015.11.010. Epub 2015 Nov 30.

Abstract

Background: Keratin 5 (K5) is a cytoskeletal tissue-specific protein expressed in the epithelial cells of skin and esophagus and ectopic K5 expression in lymphocytes has never been reported.

Objective: Here we demonstrate an ectopic epidermal self-protein expression in B-1 B cell by fate mapping of K5-expressing cells.

Methods: K5-Cre×CAG-CAT-loxP-EGFP double Tg (K5×GFP) mice that express enhanced GFP under the control of the K5 promoter were employed.

Results: Unexpectedly, B220(+)GFP(+) cells were found in LN, spleen, peripheral blood and peritoneal cavity. These cells were IgM(+)IgD(low)CD23(-)CD43(+)CD19(+)CD93(-), indicating that they were B-1 B cells. The number of B220(+)GFP(+) cells was significantly larger in spleen than in the other tissues tested. Although GFP(+) B-1 cells did not express K5 in the periphery, Lin(-)CD93(+)B220(low-neg)CD19(+) B-1 B cell progenitors expressed GFP and B220(+)CD93(+) progenitor cells expressed K5 and MHC-class II in BM, indicating that GFP(+) B-1 cells transiently expressed K5 and the progenitor cells were potential APC. GFP(+) B-1 cells in the periphery continued expressing MHC class II and had exogenous antigen-presenting capacity comparable to non-follicular B cells. GFP(+) B-1 cells spontaneously secreted more IgM than GFP(-) B-1 cells in vitro.

Conclusion: These results indicate that B-1 B cells transiently and partially express K5 in BM and are potent for both natural antibody production and antigen presentation.

Keywords: Antigen-presenting cells; B cell development; B-1 B cell; Epidermal self-protein; Self/non-self discrimination.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibody Formation
  • Antigen Presentation
  • Biomarkers / metabolism
  • Bone Marrow Cells / drug effects
  • Bone Marrow Cells / immunology
  • Bone Marrow Cells / metabolism*
  • Cell Differentiation*
  • Cell Lineage
  • Cells, Cultured
  • Genotype
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Immunoglobulin M / biosynthesis
  • Keratin-15 / genetics
  • Keratin-15 / metabolism*
  • Lipopolysaccharides / pharmacology
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Phenotype
  • Precursor Cells, B-Lymphoid / drug effects
  • Precursor Cells, B-Lymphoid / immunology
  • Precursor Cells, B-Lymphoid / metabolism*
  • Promoter Regions, Genetic
  • Time Factors

Substances

  • Biomarkers
  • Immunoglobulin M
  • Keratin-15
  • Krt15 protein, mouse
  • Lipopolysaccharides
  • enhanced green fluorescent protein
  • lipopolysaccharide, E. coli O26-B6
  • Green Fluorescent Proteins