Flexibility of single microvilli on live neutrophils and lymphocytes.
We measured the flexural stiffness of single microvilli on live human neutrophils and lymphocytes using 40-nm fluorescent beads. The beads were bound to the tips of the microvilli by anti-L-selectin antibodies. Digital bead images were acquired with an exposure time of 3 s at high magnification. Using a Gaussian point spread function, we obtained an analytical expression that relates the image profile to the flexural stiffness. We found that the flexural stiffnesses were 7 and 4 pN/microm for single microvilli on human neutrophils and lymphocytes, respectively. We also verified with live cells that 75% of neutrophil L-selectin and 72% of lymphocyte L-selectin were on the microvillus tips. Our results indicate that the leukocyte microvilli in contact with the endothelium or other surfaces will bend easily under physiological shear stresses.
Yao
Da-Kang
DK
Department of Biomedical Engineering, Washington University in Saint Louis, Saint Louis, Missouri 63130, USA.
Shao
Jin-Yu
JY
D001703:Biophysics / Q000379:methods; D002448:Cell Adhesion; D003198:Computer Simulation; D006801:Humans; D008214:Lymphocytes / Q000502:physiology*; D008856:Microscopy, Fluorescence / Q000379:methods; D008871:Microvilli / Q000378:metabolism*; D015233:Models, Statistical; D008962:Models, Theoretical; D009010:Monte Carlo Method; D018375:Neutrophil Activation; D009504:Neutrophils / Q000502:physiology*; D016011:Normal Distribution; D013314:Stress, Mechanical