UMMS Affiliation

University of Massachusetts Medical School, Department of Physiology

Publication Date


Document Type



Acrylic Resins; Animals; Cells, Cultured; Lysophospholipids; Macrophages; Mice; Mice, Inbred C3H; Microfilaments; Opsonin Proteins; Particle Size; *Phagocytosis; Receptors, Fc; Stress, Mechanical; rac1 GTP-Binding Protein


Cell Biology | Cellular and Molecular Physiology | Physiology


Phagocytosis is an actin-based process used by macrophages to clear particles greater than 0.5 microm in diameter. In addition to its role in immunological responses, phagocytosis is also necessary for tissue remodeling and repair. To prevent catastrophic autoimmune reactions, phagocytosis must be tightly regulated. It is commonly assumed that the recognition/selection of phagocytic targets is based solely upon receptor-ligand binding. Here we report an important new criterion, that mechanical parameters of the target can dramatically affect the efficiency of phagocytosis. When presented with particles of identical chemical properties but different rigidity, macrophages showed a strong preference to engulf rigid objects. Furthermore, phagocytosis of soft particles can be stimulated with the microinjection of constitutively active Rac1 but not RhoA, and with lysophosphatidic acid, an agent known to activate the small GTP-binding proteins of the Rho family. These data suggest a Rac1-dependent mechanosensory mechanism for phagocytosis, which probably plays an important role in a number of physiological and pathological processes from embryonic development to autoimmune diseases.


J Cell Sci. 2002 Feb 15;115(Pt 4):849-56.

Journal/Book/Conference Title

Journal of cell science

Related Resources

Link to Article in PubMed

PubMed ID




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