Selection of natural autoreactive B cells

Area of Science:

• Immunology
• Autoimmunity

Background:

• Natural antibodies, including anti-thymocyte autoantibody (ATA), are produced by CD5+ B1 B cells.
• Self-antigen recognition plays a role in B cell development and autoimmunity.

Purpose of the Study:

• To investigate the role of self-antigen in the accumulation and function of ATA B cells.
• To determine how varying levels of autoantigen affect B cell development and fate.

Main Methods:

• Utilized transgenic mice expressing the Ig-μ heavy chain of a prototypic ATA (V(H)3609Vκ21c).
• Analyzed B cell development and maturation in spleen under different autoantigen (Thy-1) expression levels.
• Examined the relationship between B cell receptor (BCR) crosslinking and B cell fate.

Main Results:

• Transgenic mice required self-antigen for ATA B cell accumulation and high serum ATA production.
• Most B cells were blocked at an immature stage, but some mature ATA B cells were present.
• Low autoantigen levels led to marginal zone ATA B cells; absence of antigen allowed follicular ATA B cell maturation.
• Different B cell fates at high autoantigen levels correlated with variations in responses of fetal and adult-derived B cells.

Conclusions:

• Self-antigen is essential for the development and accumulation of ATA B cells.
• BCR crosslinking and autoantigen levels critically determine B cell fate, influencing the generation of distinct B cell subsets.
• Variations in fetal and adult B cell responses to self-antigen contribute to differential B cell fates during development.