An apoptosis-dependent checkpoint for autoimmunity in memory B and plasma cells

Area of Science:

• Immunology
• Molecular Biology
• Autoimmunity

Background:

• B lymphocytes can develop self-reactivity during antibody gene diversification in bone marrow and germinal centers (GCs).
• Mechanisms controlling self-reactivity acquired in GCs are less understood than those in the bone marrow.
• Existing checkpoints effectively silence most autoreactive B cells emerging from the bone marrow.

Purpose of the Study:

• To investigate the mechanisms controlling self-reactive B cells that develop in germinal centers.
• To identify tolerance checkpoints operating on B cells after germinal center exit.
• To understand the role of programmed cell death in preventing autoimmunity.

Main Methods:

• Analysis of B cell populations in genetically modified mouse models.
• Assessment of autoantibody production.
• Evaluation of immune tolerance and autoimmunity development.

Main Results:

• Defects in germinal center B cell apoptosis did not impact autoantibody development.
• Disruption of a post-germinal center apoptosis checkpoint led to the accumulation of autoreactive memory B cells and plasma cells.
• Impaired post-GC apoptosis resulted in antinuclear antibody production and the development of autoimmunity.

Conclusions:

• An apoptosis-dependent tolerance checkpoint exists in post-germinal center B cells.
• This checkpoint is crucial for preventing the accumulation of autoreactive B cells and subsequent autoimmunity.
• Understanding this pathway offers insights into regulating immune tolerance and autoantibody generation.