Spreading of neutrophils: from activation to migration

Reflection Interference Contrast Microscopy was used to study the dynamics of neutrophil spreading. The images were analyzed to identify simultaneously the changes in the overall cell adhesion and the zones of close contact with the substrate. We show that for neutrophils, cell spreading is anisotropic and directional from the very initial stage. The curve describing the spreading area of the cell as a function of time can be fitted piecewise as power laws. Different spreading regimes are identified and related to the adhesion state and/or dynamical state of the cell. All cells follow a slow spreading, fast spreading and finally area saturation. After saturation the adhesion area of the cell fluctuates as the neutrophil migrates. Close contacts occur at opposite sides of the cell where the uropod and lamellipodium develop. The apparition of close contacts seems to indicate a change in adhesion regime.