Quantifying force-mediated antigen extraction in the B cell immune synapse using DNA-based tension sensors

Area of Science:

• Immunology
• Cell Biology
• Biophysics

Background:

• B cells engage antigen-presenting cells (APCs) to internalize antigens via B cell receptors (BCRs).
• Mechanical forces applied to BCR-antigen bonds are crucial for antigen discrimination and sensing APC properties.
• Quantifying these forces is essential for understanding B cell activation and immune synapse dynamics.

Purpose of the Study:

• To present a protocol for creating antigen-functionalized DNA tension sensors.
• To enable quantification of force-mediated antigen extraction within the B cell immune synapse.
• To provide tools for studying molecular force transfer in cell-cell interactions.

Main Methods:

• Preparation of antigen-functionalized DNA tension sensors.
• Attachment of sensors to planar lipid bilayers and quantification of surface density.
• Stimulation of B cell activation and analysis of antigen extraction using fluorescence microscopy and image analysis.

Main Results:

• Successful development and application of DNA tension sensors for B cell studies.
• Quantification of force-mediated antigen extraction efficiency in fixed cells.
• Demonstration of techniques applicable to studying force-mediated molecular transfer.

Conclusions:

• The described protocol provides a robust method for investigating force-mediated antigen uptake by B cells.
• These techniques facilitate the study of mechanical forces in immune cell interactions.
• The methodology is broadly applicable to other systems involving force-dependent molecular transfer at cell-cell contacts.