Assays of random motility of polymorphonuclear leukocytes in vitro

Combined Effect of Matrix Topography and Stiffness on Neutrophil Shape and Motility

The crawling behavior of leukocytes is driven by the cell morphology transition, which is a direct manifestation of molecular motor machinery. The topographical anisotropy and mechanical stiffness of the substrates are the main physical cues that affect leukocytes' shape generation and migratory responses. However, their combined effects on the cell morphology and motility have been poorly understood, particularly for neutrophils, which are the fastest reacting leukocytes against infections and wounds. Here, spatiotemporally correlated physical parameters are shown, which determine the neutrophil shape change during migratory processes, in response to surface topography and elasticity. Guided crawling and shape generation of individual neutrophils, activated by a uniform concentration of a chemoattractant, are analyzed by adopting elasticity-tunable micropatterning and live cell imaging techniques. Whole cell-level image analysis is performed based on a planar geometric quantification of cell shape and motility. The findings show that the pattern anisotropy and elastic modulus of the substrate induce synergic effects on the shape anisotropy, deformability, and polarization/alignment of crawling neutrophils. How the morphology-motility relationship is affected by different surface microstructures and stiffness is demonstrated. These results imply that the neutrophil shape-motility correlations can be utilized for controlling the immune cell functions with predefined physical microenvironments.

Comparative effects of antilactoferrin antibodies and tumor necrosis factor on neutrophil adherence to matrix proteins

Neutrophil adherence to matrix proteins likely plays an important role in inflammatory responses. Antineutrophil cytoplasm antibodies may activate neutrophils in certain diseases. Using an in vitro method that allows simultaneous quantitation of neutrophil adherence and superoxide secretion, we compared the effects of antibodies against neutrophil granule proteins and tumor necrosis factor alpha (TNF-alpha), a known neutrophil agonist. Antilactoferrin antibodies but not antielastase or antimyeloperoxidase antibodies stimulated increased adherence to fibronectin and laminin similar in degree to that induced by TNF-alpha. This, but not the simultaneous superoxide secretion, was inhibited in the presence of anti-CD18 antibodies. Humoral immune responses to lactoferrin, likely expressed on the neutrophil surface, can activate neutrophils in proinflammatory responses that may be pathogenic.