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Updated: Jun 10, 2026
Basophil Activation Test for Allergy Diagnosis
Published on: May 31, 2021
Distribution and dynamics of rat basophilic leukemia immunoglobulin E receptors (FcepsilonRI) on planar
Kathrin Spendier1, Amanda Carroll-Portillo, Keith A Lidke
1Consortium of the Americas for Interdisciplinary Science, Department of Pathology, University of New Mexico, Albuquerque, New Mexico, USA.
Insights
Immunoglobulin E receptors cluster on mast cells upon ligand binding, driven by diffusion to contact sites. This receptor clustering dynamics mirrors membrane fluctuations, suggesting shared cellular machinery.
Area of Science:
- Cellular Biology
- Immunology
- Biophysics
Background:
- Signaling mechanisms of immunoreceptors are crucial, particularly when activated by membrane-bound ligands.
- Understanding receptor dynamics is key to elucidating cellular responses in immunology.
Purpose of the Study:
- To quantify the spatiotemporal dynamics of immunoglobulin E receptors (IgE-FcεRI) redistribution on mast cells.
- To investigate receptor clustering mechanisms upon engagement with membrane-bound ligands.
Main Methods:
- Utilized micropipette cell manipulation for precise control of cell-surface contact initiation (+/-50 ms).
- Employed total internal reflection fluorescence microscopy to track receptor dynamics on rat basophilic leukemia-2H3 mast cells.
- Studied cells interacting with both fluid and gel-phase membranes displaying immunoglobulin E ligands.
Main Results:
- Receptor clusters formed at micron-scale heterogeneities on ligand-presenting surfaces, mirroring ligand-free surface patterns.
- Initial receptor accumulation into clusters suggested diffusion-limited trapping (D ≈ 10⁻¹ μm²/s).
- Post-formation, clusters exhibited both diffusive and directed motion, similar to membrane fluctuations.
Conclusions:
- Receptor cluster formation is driven by diffusion to cell-surface contact regions.
- The cellular machinery governing membrane fluctuations may also regulate IgE-FcεRI cluster dynamics.
- These findings provide insights into the early events of mast cell activation and signaling.
Abstract:
There is considerable interest in the signaling mechanisms of immunoreceptors, especially when triggered with membrane-bound ligands. We have quantified the spatiotemporal dynamics of the redistribution of immunoglobulin E-loaded receptors (IgE-FcepsilonRI) on rat basophilic leukemia-2H3 mast cells in contact with fluid and gel-phase membranes displaying ligands for immunoglobulin E, using total internal reflection fluorescence microscopy. To clearly separate the kinetics of receptor redistribution from cell spreading, and to precisely define the initial contact time (+/-50 ms), micropipette cell manipulation was used to bring individual cells into contact with surfaces. On ligand-free surfaces, there are micron-scale heterogeneities in fluorescence that likely reflect regions of the cell that are more closely apposed to the substrate. When ligands are present, receptor clusters form with this same size scale. The initial rate of accumulation of receptors into the clusters is consistent with diffusion-limited trapping with D approximately 10(-1) microm2/s. These results support the hypothesis that clusters form by diffusion to cell-surface contact regions. Over longer timescales (>10 s), individual clusters moved with both diffusive and directed motion components. The dynamics of the cluster motion is similar to the dynamics of membrane fluctuations of cells on ligand-free fluid membranes. Thus, the same cellular machinery may be responsible for both processes.
