Target cell cortical tension regulates macrophage trogocytosis

Area of Science:

• Immunology
• Cell Biology
• Biophysics

Background:

• Macrophages engulf cellular material through phagocytosis and trogocytosis.
• The decision-making process for macrophages choosing between trogocytosis and phagocytosis remains poorly understood.
• Trogocytosis involves engulfing small membrane fragments, while phagocytosis involves complete engulfment.

Purpose of the Study:

• To investigate the factors influencing macrophage choice between trogocytosis and phagocytosis.
• To determine the role of target cell mechanical properties in regulating these cellular processes.

Main Methods:

• Utilized antibody-opsonized cells and model vesicles with varying cortical tension.
• Manipulated target cell membrane tension and cortex stiffness.
• Observed macrophage interactions using microscopy and developed a mechanical model.

Main Results:

• Low target cell cortical tension promoted preferential trogocytosis by macrophages.
• High target cell cortical tension shifted macrophage behavior towards phagocytosis.
• Increased antibody surface density could counteract the phagocytosis-promoting effect of high tension.

Conclusions:

• Target cell cortical tension is a critical determinant of whether macrophages engage in trogocytosis or phagocytosis.
• The mechanical properties of the target cell, not distinct macrophage pathways, primarily govern the engulfment outcome.
• Macrophages dynamically switch between trogocytosis and phagocytosis in response to changes in target cell tension.