Differences in Self-Recognition between Secreted Antibody and Membrane-Bound B Cell Antigen Receptor

Area of Science:

• Immunology
• Molecular Biology
• Cell Biology

Background:

• B cell development involves random gene segment rearrangement, crucial for antibody (Ab) repertoire diversity.
• Potential generation of autoreactive specificities necessitates stringent selection mechanisms to eliminate autoreactive B cells.
• Conventional assays for autoreactive B cells often use in vitro-generated Abs, which may differ from membrane-bound B cell receptors (BCRs).

Purpose of the Study:

• To investigate the autoreactivity of membrane-bound BCRs across various human peripheral blood B cell developmental stages.
• To compare the autoreactivity detected by a cell-based assay with conventional methods using soluble Abs.

Main Methods:

• Development and application of a novel cell-based assay to detect autoreactivity of membrane-bound BCRs.
• Testing of membrane-bound BCRs from different human B cell developmental stages.
• Comparison with conventional assays using in vitro-generated soluble Abs.

Main Results:

• A limited number of tested membrane-bound BCRs exhibited autoreactivity when assessed via the cell-based assay.
• The cell-based assay demonstrated high sensitivity, detecting weak antigen recognition by a germline-reverted murine BCR, a feat missed by conventional assays.
• Soluble Ab counterparts showed differing reactivity compared to their membrane-bound BCR forms.

Conclusions:

• Accurate identification of autoreactive B cells necessitates the use of membrane-bound BCRs.
• Soluble Abs may not reliably reflect the antigen-binding properties of their corresponding membrane-bound BCRs.
• The study underscores the importance of the BCR's membrane-bound form in assessing B cell autoreactivity.