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Non-overlapping Fas- and BCL-2-regulated death pathways in IgG2a(b)-producing B cells
1Unité d'Immunophysiologie Moléculaire, Institut Pasteur, 25 rue du Docteur-Roux, 75724 Paris Cedex 15, France.
International Immunology
|July 6, 2000
Summary
T cells can eliminate specific B cells, causing IgG2a(b) allotype suppression. Overexpressed BCL-2 protein did not prevent Fas-mediated B cell death, indicating non-overlapping death pathways in this immune regulation model.
Area of Science:
- Immunology
- Cell Biology
Background:
- T cells eliminate B cells via perforin (Pfp) or Fas pathways, leading to IgG2a(b) allotype suppression.
- The role of BCL-2 oncoprotein in Fas-mediated cell death is debated.
Purpose of the Study:
- To investigate the impact of BCL-2 overexpression on Fas-mediated B cell death during IgG2a(b) allotype suppression.
Main Methods:
- Used transgenic mice with overexpressed human BCL-2 in B cells.
- Exposed these B cells to Fas-dependent cytotoxic T cell activity from Igh(a/a) Pfp(0/0) mice in vivo.
- Assessed IgG2a(b) suppression and BCL-2 pathway regulation.
Main Results:
- Constitutive BCL-2 overexpression did not prevent Fas-mediated elimination of IgG2a(b)-producing B cells.
- Total and chronic IgG2a(b) suppression occurred despite high BCL-2 levels.
- Fas signaling, via caspase 8, did not involve BCL-2-regulated mitochondria-dependent pathways.
Conclusions:
- Fas- and BCL-2-regulated cell death mechanisms are distinct in this model of Ig production regulation.
- BCL-2 does not protect mature B cells from Fas-mediated cytotoxicity in this context.