Cell movement analysis in a necrotactic assay.

The methods of statistical physics have been applied to analysis of cell movement. Human leukocytes (granulocytes) were observed using time-lapse photography. The paths of the migrating cells were determined. The chemokinetic response at 35 degrees C is described by the diffusion constant (D = 233 micron2/min) and the track velocity (25 micron/min). A time-dependent chemotactic gradient is created by killing an erythrocyte by an intense laser flash. The chemotactic response at 35 degrees C is described by the degree of polar orientation (P1 = 0.85), the track velocity 24 micron/min, and the drift velocity towards the necrotactic source (v parallel = 20 micron/min). The track velocity as well the drift velocity show a broad distribution. The half-width of the velocity distribution. The half-width of the velocity distribution is approximately 5 micron/min. Cell movement can be described by elementary moving states. The characteristic time of the internal clock of the migrating cell is approximately 0.5 min. We found that the information transfer from the necrotactic gradient to the migrating cell is 1 bit per change in directed movement. A migrating cell cannot be stimulated within a period of approximately 10 s after the last decision to adapt a new moving direction.