Nanobody-CD16 Catch Bond Reveals NK Cell Mechanosensitivity

Area of Science:

• Biophysics
• Immunology
• Biotechnology

Background:

• Antibodies are vital in research and medicine, traditionally characterized by solution-based affinity.
• Physiological conditions involve mechanical forces on antibody bonds, particularly in antibody-dependent cell cytotoxicity (ADCC).
• Investigating 2D antigen-antibody binding under force is essential for predicting in vivo antibody function.

Purpose of the Study:

• To investigate antigen-antibody binding kinetics under force in a 2D environment.
• To characterize the mechanical properties of anti-CD16 nanobody interactions.
• To explore the implications of these findings for therapeutic antibody design.

Main Methods:

• Utilized a laminar flow chamber assay to measure single anti-CD16 nanobody-CD16 antigen bond kinetics.
• Simulated 2D encounters between surface-bound nanobodies and microsphere-bound antigens.
• Quantified natural killer cell spreading on nanobody-coated surfaces.

Main Results:

• Both nanobodies showed similar 2D association kinetics dependent on encounter duration.
• One nanobody displayed slip-bond behavior (off-rate increases with force).
• The other nanobody exhibited catch-bond behavior (off-rate decreases with force), a novel finding for antigen-antibody interactions.
• Cellular adhesion assays supported natural killer cell mechanosensitivity.

Conclusions:

• Antigen-antibody interactions can exhibit catch-bond behavior, challenging classical affinity measurements.
• These findings provide insights into antibody function under mechanical force in 2D.
• Results have significant implications for designing effective bispecific antibodies for therapeutic use.