[Breakdown of B cell-tolerance and its genetic control]

Area of Science:

• Immunology
• Autoimmunity
• Cell Biology

Background:

• Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoantibody production.
• B cells play a critical role in SLE pathogenesis.
• Fas-mediated apoptosis is a key mechanism for eliminating self-reactive lymphocytes.

Purpose of the Study:

• To investigate Fas expression and apoptosis sensitivity in autoantibody-producing B cells from (NZB x NZW)F1 mice, a model for SLE.
• To determine the relationship between Fas expression, apoptosis resistance, and anti-DNA antibody production.

Main Methods:

• Flow cytometry was used to assess Fas expression on B cells.
• Apoptosis sensitivity was evaluated following stimulation.
• Anti-DNA antibody production was measured in different B cell subsets.

Main Results:

• In young (NZB x NZW)F1 mice, B cells expressed low Fas but up-regulated it upon anti-CD40 mAb stimulation, dividing them into Fas(high) (apoptosis-sensitive) and Fas(low) (apoptosis-resistant) populations.
• A significant proportion of B cells in aged mice with overt SLE spontaneously exhibited a Fas(low), apoptosis-resistant phenotype.
• Anti-DNA antibodies were predominantly produced by the apoptosis-resistant, Fas(low) B cell subset in both young and aged mice.

Conclusions:

• Apoptosis-resistant B cells with low Fas expression are the main source of anti-DNA antibodies in (NZB x NZW)F1 mice.
• The expansion of these resistant B cells may contribute to the development and progression of SLE.
• Targeting Fas-mediated apoptosis pathways in B cells could be a potential therapeutic strategy for SLE.