Editing and escape from editing in anti-DNA B cells

Area of Science:

• Immunology
• Molecular Biology
• Cell Biology

Background:

• Tolerance to self-reactive B cells, particularly those targeting double-stranded DNA (dsDNA), is crucial for preventing autoimmunity.
• B cell receptor (BCR) editing is a primary mechanism for eliminating self-reactive B cells during development.
• Failure of BCR editing can lead to the escape of self-reactive B cells into the periphery.

Purpose of the Study:

• To investigate the mechanisms by which B cells with anti-dsDNA receptors evade central tolerance.
• To identify the characteristics and peripheral localization of self-reactive B cells that escape tolerance.
• To understand the role of intracellular IgM accumulation and co-expressed antigens in B cell tolerance evasion.

Main Methods:

• Analysis of hybridomas derived from anti-dsDNA heavy chain transgenic mice.
• Immunofluorescence staining to detect intracellular and cell surface IgM.
• Flow cytometry to assess cell surface markers, including CD21 and CD23.
• Characterization of B cells binding to dsDNA and a Golgi-associated antigen.

Main Results:

• Some B cells with anti-dsDNA receptors escape editing and migrate to the spleen.
• These B cells bind an additional Golgi-associated antigen, leading to intracellular IgM accumulation.
• Intracellular IgM accumulation is incomplete, with surface IgM clusters observed.
• Escaped B cells exhibit a CD21-high/CD23-low phenotype, characteristic of marginal zone B cells.

Conclusions:

• Expression of an immunoglobulin (Ig) binding dsDNA and an additional secretory compartment antigen confers resistance to central B cell tolerance.
• These self-reactive B cells may be sequestered in the splenic marginal zone, representing a potential source of autoimmune pathology.
• The findings shed light on novel pathways of B cell tolerance evasion and the potential origins of anti-dsDNA autoantibodies.