Human naive B cells cultured with EL-4 T cells mimic a germinal center-related B cell stage before generating plasma cells. Concordant changes in Bcl-2 protein and messenger RNA levels

Eur J Immunol. 1997 Jan;27(1):199-205. doi: 10.1002/eji.1830270130.


The T cell-dependent B cell response in vivo occurs in organized microenvironments. Alternative routes exist in that early plasma cells are generated in the T zone while others emerge later from the germinal center (GC) reaction. We investigated whether B cell stages resembling those defined in vivo/ex vivo might be induced in an in vitro system in which naive human B cells are activated by EL-4 T cells and cytokines. Adult peripheral blood- or cord blood-derived B cells were found to mimic an early activated stage (CD38(low), IgD+, increased CD5+) followed by a centroblastic GC-related stage (CD38(int), CD77+, CD95(Fas)+, Bcl-2 protein(low)) before differentiating into morphologically typical, CD38(high), Fas- plasma cells of an immature type (Bcl-2(low), VLA-5-). The GC-related cells and the plasma cells exhibited spontaneous apoptosis in medium, the former also undergoing anti-Fas antibody-induced apoptosis in medium as well as during CD40L exposure in the EL-4 cultures. These Bcl-2(low) cells maintained a high viability in contact with EL-4 cells. Thus, some, major B cell stages with typical functional features as described for cells in vivo/ex vivo are sequentially generated in this in vitro system and the kinetics of the changes can be analyzed in a synchronized cell population. With regard to previous apparently conflicting observations on the Bcl-2 mRNA level in GC B cells, we performed competitive reverse-transcription polymerase chain reaction. Concordant changes in Bcl-2 mRNA and protein levels were found, i.e. during Bcl-2 down-regulation in the GC-related B cells in ongoing EL-4 cultures or in medium, and during a more modest up-regulation upon contact with fresh EL-4 cells. Regulation of Bcl-2 protein, therefore, predominantly occurred at the mRNA steady-state level.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Apoptosis
  • B-Lymphocytes / cytology*
  • B-Lymphocytes / immunology
  • Cell Differentiation
  • Cells, Cultured
  • DNA / analysis
  • Fetal Blood
  • Gene Expression
  • Germinal Center / cytology
  • Germinal Center / immunology
  • Hematopoiesis
  • Humans
  • Plasma Cells / cytology
  • Plasma Cells / immunology
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • RNA, Messenger / genetics
  • beta 2-Microglobulin / genetics
  • fas Receptor / analysis


  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Messenger
  • beta 2-Microglobulin
  • fas Receptor
  • DNA